Program to convert a given number to words

Write code to convert a given number into words. For example, if “1234” is given as input, the output should be “one thousand two hundred thirty-four”.

Following is the implementation for the same. The code supports numbers up to 4 digits, i.e., numbers from 0 to 9999. Idea is to create arrays that store individual parts of output strings. One array is used for single digits, one for numbers from 10 to 19, one for 20, 30, 40, 50, .. etc, and one for powers of 10. 
The given number is divided into two parts: the first two digits and the last two digits, and the two parts are printed separately. 

C++

// CPP program to print a given number in words. The program
// handles numbers from 0 to 9999

#include <bits/stdc++.h>
using namespace std;

// A function that prints given number in words
void convert_to_words(char* num)
{
    int len = strlen(
        num); // Get number of digits in given number

    // Base cases
    if (len == 0) {
        fprintf(stderr, "empty string\n");
        return;
    }
    if (len > 4) {
        fprintf(stderr,
                "Length more than 4 is not supported\n");
        return;
    }

    /* The first string is not used, it is to make
        array indexing simple */
    char* single_digits[]
        = { "zero", "one", "two",   "three", "four",
            "five", "six", "seven", "eight", "nine" };

    /* The first string is not used, it is to make
        array indexing simple */
    char* two_digits[]
        = { "",          "ten",      "eleven",  "twelve",
            "thirteen",  "fourteen", "fifteen", "sixteen",
            "seventeen", "eighteen", "nineteen" };

    /* The first two string are not used, they are to make
        array indexing simple*/
    char* tens_multiple[] = { "",       "",        "twenty",
                              "thirty", "forty",   "fifty",
                              "sixty",  "seventy", "eighty",
                              "ninety" };

    char* tens_power[] = { "hundred", "thousand" };

    // Used for debugging purpose only
    cout << "\n" << num << ": ";

    // For single digit number
    if (len == 1) {
        cout << single_digits[*num - '0'] << "\n";
        return;
    }

    // Iterate while num is not '\0'
    while (*num != '\0') {

        // Code path for first 2 digits
        if (len >= 3) {
            if (*num - '0' != 0) {
                cout << single_digits[*num - '0'] << " ";
                cout << tens_power[len - 3]
                     << " "; // here len can be 3 or 4
            }
            --len;
        }

        // Code path for last 2 digits
        else {
            /* Need to explicitly handle 10-19. Sum of the
            two digits is used as index of "two_digits"
            array of strings */
            if (*num == '1') {
                int sum = *num - '0' + *(num + 1) - '0';
                cout << two_digits[sum] << "\n";
                return;
            }

            // Need to explicitly handle 20
            else if (*num == '2' && *(num + 1) == '0') {
                cout << "twenty\n";
                return;
            }

            // Rest of the two digit numbers i.e., 21 to 99
            else {
                int i = *num - '0';
                string tm = i ? tens_multiple[i] : "";
                cout << tm << " ";
                ++num;
                if (*num != '0')
                    cout << single_digits[*num - '0']
                         << " ";
            }
        }
        ++num;
    }
}

// Driver program to test above function
int main()
{
    convert_to_words("9923");
    convert_to_words("523");
    convert_to_words("89");
    convert_to_words("8");

    return 0;
}

// This code is contributed by Susobhan Akhuli

C

/* C program to print a given number in words. The program
handles numbers from 0 to 9999 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* A function that prints given number in words */
void convert_to_words(char* num)
{
    int len = strlen(
        num); // Get number of digits in given number

    /* Base cases */
    if (len == 0) {
        fprintf(stderr, "empty string\n");
        return;
    }
    if (len > 4) {
        fprintf(stderr,
                "Length more than 4 is not supported\n");
        return;
    }

    /* The first string is not used, it is to make
        array indexing simple */
    char* single_digits[]
        = { "zero", "one", "two",   "three", "four",
            "five", "six", "seven", "eight", "nine" };

    /* The first string is not used, it is to make
        array indexing simple */
    char* two_digits[]
        = { "",          "ten",      "eleven",  "twelve",
            "thirteen",  "fourteen", "fifteen", "sixteen",
            "seventeen", "eighteen", "nineteen" };

    /* The first two string are not used, they are to make
        array indexing simple*/
    char* tens_multiple[] = { "",       "",        "twenty",
                              "thirty", "forty",   "fifty",
                              "sixty",  "seventy", "eighty",
                              "ninety" };

    char* tens_power[] = { "hundred", "thousand" };

    /* Used for debugging purpose only */
    printf("\n%s: ", num);

    /* For single digit number */
    if (len == 1) {
        printf("%s\n", single_digits[*num - '0']);
        return;
    }

    /* Iterate while num is not '\0' */
    while (*num != '\0') {

        /* Code path for first 2 digits */
        if (len >= 3) {
            if (*num - '0' != 0) {
                printf("%s ", single_digits[*num - '0']);
                printf("%s ",
                       tens_power[len - 3]); // here len can
                                             // be 3 or 4
            }
            --len;
        }

        /* Code path for last 2 digits */
        else {
            /* Need to explicitly handle 10-19. Sum of the
            two digits is used as index of "two_digits"
            array of strings */
            if (*num == '1') {
                int sum = *num - '0' + *(num + 1) - '0';
                printf("%s\n", two_digits[sum]);
                return;
            }

            /* Need to explicitly handle 20 */
            else if (*num == '2' && *(num + 1) == '0') {
                printf("twenty\n");
                return;
            }

            /* Rest of the two digit numbers i.e., 21 to 99
             */
            else {
                int i = *num - '0';
                printf("%s ", i ? tens_multiple[i] : "");
                ++num;
                if (*num != '0')
                    printf("%s ",
                           single_digits[*num - '0']);
            }
        }
        ++num;
    }
}

/* Driver program to test above function */
int main(void)
{
    convert_to_words("9923");
    convert_to_words("523");
    convert_to_words("89");
    convert_to_words("8");

    return 0;
}

Java

// Java program to print a given number in words. The
// program handles numbers from 0 to 9999

class GFG {
    // A function that prints
    // given number in words
    static void convert_to_words(char[] num)
    {
        // Get number of digits
        // in given number
        int len = num.length;

        // Base cases
        if (len == 0) {
            System.out.println("empty string");
            return;
        }
        if (len > 4) {
            System.out.println(
                "Length more than 4 is not supported");
            return;
        }

        /* The first string is not used, it is to make
            array indexing simple */
        String[] single_digits = new String[] {
            "zero", "one", "two",   "three", "four",
            "five", "six", "seven", "eight", "nine"
        };

        /* The first string is not used, it is to make
            array indexing simple */
        String[] two_digits = new String[] {
            "",          "ten",      "eleven",  "twelve",
            "thirteen",  "fourteen", "fifteen", "sixteen",
            "seventeen", "eighteen", "nineteen"
        };

        /* The first two string are not used, they are to
         * make array indexing simple*/
        String[] tens_multiple = new String[] {
            "",      "",      "twenty",  "thirty", "forty",
            "fifty", "sixty", "seventy", "eighty", "ninety"
        };

        String[] tens_power
            = new String[] { "hundred", "thousand" };

        /* Used for debugging purpose only */
        System.out.print(String.valueOf(num) + ": ");

        /* For single digit number */
        if (len == 1) {
            System.out.println(single_digits[num[0] - '0']);
            return;
        }

        /* Iterate while num
            is not '\0' */
        int x = 0;
        while (x < num.length) {

            /* Code path for first 2 digits */
            if (len >= 3) {
                if (num[x] - '0' != 0) {
                    System.out.print(
                        single_digits[num[x] - '0'] + " ");
                    System.out.print(tens_power[len - 3]
                                     + " ");
                    // here len can be 3 or 4
                }
                --len;
            }

            /* Code path for last 2 digits */
            else {
                /* Need to explicitly handle
                10-19. Sum of the two digits
                is used as index of "two_digits"
                array of strings */
                if (num[x] - '0' == 1) {
                    int sum
                        = num[x] - '0' + num[x + 1] - '0';
                    System.out.println(two_digits[sum]);
                    return;
                }

                /* Need to explicitly handle 20 */
                else if (num[x] - '0' == 2
                         && num[x + 1] - '0' == 0) {
                    System.out.println("twenty");
                    return;
                }

                /* Rest of the two digit
                numbers i.e., 21 to 99 */
                else {
                    int i = (num[x] - '0');
                    if (i > 0)
                        System.out.print(tens_multiple[i]
                                         + " ");
                    else
                        System.out.print("");
                    ++x;
                    if (num[x] - '0' != 0)
                        System.out.println(
                            single_digits[num[x] - '0']);
                }
            }
            ++x;
        }
    }

    // Driver Code
    public static void main(String[] args)
    {
        convert_to_words("9923".toCharArray());
        convert_to_words("523".toCharArray());
        convert_to_words("89".toCharArray());
        convert_to_words("8".toCharArray());
    }
}
// This code is contributed
// by Mithun Kumar

Python3

# Python program to print a given number in
# words. The program handles numbers
# from 0 to 9999

# A function that prints
# given number in words


def convert_to_words(num):

    # Get number of digits
    # in given number
    l = len(num)

    # Base cases
    if (l == 0):
        print("empty string")
        return

    if (l > 4):
        print("Length more than 4 is not supported")
        return

    # The first string is not used,
    # it is to make array indexing simple
    single_digits = ["zero", "one", "two", "three",
                     "four", "five", "six", "seven",
                     "eight", "nine"]

    # The first string is not used,
    # it is to make array indexing simple
    two_digits = ["", "ten", "eleven", "twelve",
                  "thirteen", "fourteen", "fifteen",
                  "sixteen", "seventeen", "eighteen",
                  "nineteen"]

    # The first two string are not used,
    # they are to make array indexing simple
    tens_multiple = ["", "", "twenty", "thirty", "forty",
                     "fifty", "sixty", "seventy", "eighty",
                     "ninety"]

    tens_power = ["hundred", "thousand"]

    # Used for debugging purpose only
    print(num, ":", end=" ")

    # For single digit number
    if (l == 1):
        print(single_digits[ord(num[0]) - 48])
        return

    # Iterate while num is not '\0'
    x = 0
    while (x < len(num)):

        # Code path for first 2 digits
        if (l >= 3):
            if (ord(num[x]) - 48 != 0):
                print(single_digits[ord(num[x]) - 48],
                      end=" ")
                print(tens_power[l - 3], end=" ")
                # here len can be 3 or 4

            l -= 1

        # Code path for last 2 digits
        else:

            # Need to explicitly handle
            # 10-19. Sum of the two digits
            # is used as index of "two_digits"
            # array of strings
            if (ord(num[x]) - 48 == 1):
                sum = (ord(num[x]) - 48 +
                       ord(num[x+1]) - 48)
                print(two_digits[sum])
                return

            # Need to explicitly handle 20
            elif (ord(num[x]) - 48 == 2 and
                  ord(num[x + 1]) - 48 == 0):
                print("twenty")
                return

            # Rest of the two digit
            # numbers i.e., 21 to 99
            else:
                i = ord(num[x]) - 48
                if(i > 0):
                    print(tens_multiple[i], end=" ")
                else:
                    print("", end="")
                x += 1
                if(ord(num[x]) - 48 != 0):
                    print(single_digits[ord(num[x]) - 48])
        x += 1


# Driver Code
convert_to_words("9923") # Four Digits
convert_to_words("523") # Three Digits
convert_to_words("89") # Two Digits
convert_to_words("8") # One Digits

# This code is contributed
# by Mithun Kumar

C#

// C# program to print a given
// number in words. The program
// handles numbers from 0 to 9999
using System;

class GFG {
    // A function that prints
    // given number in words
    static void convert_to_words(char[] num)
    {
        // Get number of digits
        // in given number
        int len = num.Length;

        // Base cases
        if (len == 0) {
            Console.WriteLine("empty string");
            return;
        }
        if (len > 4) {
            Console.WriteLine("Length more than "
                              + "4 is not supported");
            return;
        }

        /* The first string is not used,
           it is to make array indexing simple */
        string[] single_digits = new string[] {
            "zero", "one", "two",   "three", "four",
            "five", "six", "seven", "eight", "nine"
        };

        /* The first string is not used,
           it is to make array indexing simple */
        string[] two_digits = new string[] {
            "",          "ten",      "eleven",  "twelve",
            "thirteen",  "fourteen", "fifteen", "sixteen",
            "seventeen", "eighteen", "nineteen"
        };

        /* The first two string are not used,
           they are to make array indexing simple*/
        string[] tens_multiple = new string[] {
            "",      "",      "twenty",  "thirty", "forty",
            "fifty", "sixty", "seventy", "eighty", "ninety"
        };

        string[] tens_power
            = new string[] { "hundred", "thousand" };

        /* Used for debugging purpose only */
        Console.Write((new string(num)) + ": ");

        /* For single digit number */
        if (len == 1) {
            Console.WriteLine(single_digits[num[0] - '0']);
            return;
        }

        /* Iterate while num
            is not '\0' */
        int x = 0;
        while (x < num.Length) {

            /* Code path for first 2 digits */
            if (len >= 3) {
                if (num[x] - '0' != 0) {
                    Console.Write(
                        single_digits[num[x] - '0'] + " ");
                    Console.Write(tens_power[len - 3]
                                  + " ");

                    // here len can be 3 or 4
                }
                --len;
            }

            /* Code path for last 2 digits */
            else {
                /* Need to explicitly handle
                10-19. Sum of the two digits
                is used as index of "two_digits"
                array of strings */
                if (num[x] - '0' == 1) {
                    int sum = num[x] - '0' + num[x + 1] - '0';
                    Console.WriteLine(two_digits[sum]);
                    return;
                }

                /* Need to explicitly handle 20 */
                else if (num[x] - '0' == 2
                         && num[x + 1] - '0' == 0) {
                    Console.WriteLine("twenty");
                    return;
                }

                /* Rest of the two digit
                numbers i.e., 21 to 99 */
                else {
                    int i = (num[x] - '0');
                    if (i > 0)
                        Console.Write(tens_multiple[i]
                                      + " ");
                    else
                        Console.Write("");
                    ++x;
                    if (num[x] - '0' != 0)
                        Console.WriteLine(
                            single_digits[num[x] - '0']);
                }
            }
            ++x;
        }
    }

    // Driver Code
    public static void Main()
    {
        convert_to_words("9923".ToCharArray());
        convert_to_words("523".ToCharArray());
        convert_to_words("89".ToCharArray());
        convert_to_words("8".ToCharArray());
    }
}

// This code is contributed
// by Mits

PHP

<?php
// PHP program to print a given
// number in words. The
// program handles numbers
// from 0 to 9999

// A function that prints
// given number in words
function convert_to_words($num)
{
    // Get number of digits
    // in given number
    $len = strlen($num);

    // Base cases
    if ($len == 0)
    {
        echo "empty string\n";
        return;
    }
    if ($len > 4)
    {
        echo "Length more than 4 " .
               "is not supported\n";
        return;
    }

    /* The first string is not used,
    it is to make array indexing simple */
    $single_digits = array("zero", "one", "two",
                           "three", "four", "five",
                           "six", "seven", "eight",
                                           "nine");

    /* The first string is not used,
    it is to make array indexing simple */
    $two_digits = array("", "ten", "eleven", "twelve",
                        "thirteen", "fourteen", "fifteen",
                        "sixteen", "seventeen", "eighteen",
                                               "nineteen");

    /* The first two string are not used,
    they are to make array indexing simple*/
    $tens_multiple = array("", "", "twenty", "thirty",
                           "forty", "fifty", "sixty",
                           "seventy", "eighty", "ninety");

    $tens_power = array("hundred", "thousand");

    /* Used for debugging purpose only */
    echo $num.": ";

    /* For single digit number */
    if ($len == 1)
    {
        echo $single_digits[$num[0] - '0'] . " \n";
        return;
    }

    /* Iterate while num
        is not '\0' */
    $x = 0;
    while ($x < strlen($num))
    {

        /* Code path for first 2 digits */
        if ($len >= 3)
        {
            if ($num[$x]-'0' != 0)
            {
                echo $single_digits[$num[$x] - '0'] . " ";
                echo $tens_power[$len - 3] . " ";
                // here len can be 3 or 4
            }
            --$len;
        }

        /* Code path for last 2 digits */
        else
        {
            /* Need to explicitly handle
            10-19. Sum of the two digits
            is used as index of "two_digits"
            array of strings */
            if ($num[$x] - '0' == 1)
            {
                $sum = $num[$x] - '0' +
                       $num[$x] - '0';
                echo $two_digits[$sum] . " \n";
                return;
            }

            /* Need to explicitly handle 20 */
            else if ($num[$x] - '0' == 2 &&
                     $num[$x + 1] - '0' == 0)
            {
                echo "twenty\n";
                return;
            }

            /* Rest of the two digit
            numbers i.e., 21 to 99 */
            else
            {
                $i = $num[$x] - '0';
                if($i > 0)
                echo $tens_multiple[$i] . " ";
                else
                echo "";
                ++$x;
                if ($num[$x] - '0' != 0)
                    echo $single_digits[$num[$x] -
                                     '0'] . " \n";
            }
        }
        ++$x;
    }
}

// Driver Code
convert_to_words("9923");
convert_to_words("523");
convert_to_words("89");
convert_to_words("8");

// This code is contributed
// by Mithun Kumar
?>

Javascript

<script>

// JavaScript program to document.write a given number in
// words. The program handles numbers
// from 0 to 9999

// A function that document.writes
// given number in words
function convert_to_words(num){

    // Get number of digits
    // in given number
    let l = num.length

    // Base cases
    if (l == 0){
        document.write("empty string","</br>")
        return
    }

    if (l > 4){
        document.write("Length more than 4 is not supported","</br>")
        return
    }

    // The first string is not used,
    // it is to make array indexing simple
    let single_digits = ["zero", "one", "two", "three",
                     "four", "five", "six", "seven",
                     "eight", "nine"]

    // The first string is not used,
    // it is to make array indexing simple
    let two_digits = ["", "ten", "eleven", "twelve",
                  "thirteen", "fourteen", "fifteen",
                  "sixteen", "seventeen", "eighteen",
                  "nineteen"]

    // The first two string are not used,
    // they are to make array indexing simple
    let tens_multiple = ["", "", "twenty", "thirty", "forty",
                     "fifty", "sixty", "seventy", "eighty",
                     "ninety"]

    let tens_power = ["hundred", "thousand"]

    // Used for debugging purpose only
    document.write(num, ":"," ")

    // For single digit number
    if (l == 1){
        document.write(single_digits[num.charCodeAt(0) - 48],"</br>")
        return
    }

    // Iterate while num is not '\0'
    let x = 0
    while (x < num.length){

        // Code path for first 2 digits
        if (l >= 3){
            if (num.charCodeAt(x) - 48 != 0){
                document.write(single_digits[num.charCodeAt(x) - 48]," ")
                document.write(tens_power[l - 3]," ")
                // here len can be 3 or 4
            }

            l -= 1
        }

        // Code path for last 2 digits
        else{

            // Need to explicitly handle
            // 10-19. Sum of the two digits
            // is used as index of "two_digits"
            // array of strings
            if (num.charCodeAt(x) - 48 == 1){
                sum = (num.charCodeAt(x) - 48 + num.charCodeAt(x+1) - 48)
                document.write(two_digits[sum],"</br>")
                return
            }

            // Need to explicitly handle 20
            else if (num.charCodeAt(x) - 48 == 2 &&
                  num.charCodeAt(x + 1) - 48 == 0){
                document.write("twenty","</br>")
                return
            }

            // Rest of the two digit
            // numbers i.e., 21 to 99
            else{
                i = num.charCodeAt(x) - 48
                if(i > 0)
                    document.write(tens_multiple[i], end=" ")
                else
                    document.write("", end="")
                x += 1
                if(num.charCodeAt(x) - 48 != 0)
                    document.write(single_digits[num.charCodeAt(x) - 48],"</br>")
            }
        }
        x += 1
    }

}

// Driver Code
convert_to_words("9923") // Four Digits
convert_to_words("523") // Three Digits
convert_to_words("89") // Two Digits
convert_to_words("8") // One Digits

// This code is contributed by shinjanpatra

</script>

Output

9923: nine thousand nine hundred twenty three 
523: five hundred twenty three 
89: eighty nine 
8: eight

Time Complexity: O(N) [N is the length of the string]
Auxiliary Space: O(1)

This article is compiled by Narendra Kangralkar. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

Approach 2: The following code supports numbers up to 15 digits, i.e., numbers from 0 to trillions. The code prints according to the western number system.

Below is the implementation:

C++

#include <bits/stdc++.h>
using namespace std;
string numberToWords(long long int n)
{
    long long int limit = 1000000000000, curr_hun, t = 0;
    // If zero return zero
    if (n == 0)
        return ("Zero");
    // Array to store the powers of 10
    string multiplier[] = { "", "Trillion", "Billion",
                            "Million", "Thousand" };
    // Array to store numbers till 20
    string first_twenty[] = {
        "",        "One",       "Two",      "Three",
        "Four",    "Five",      "Six",      "Seven",
        "Eight",   "Nine",      "Ten",      "Eleven",
        "Twelve",  "Thirteen",  "Fourteen", "Fifteen",
        "Sixteen", "Seventeen", "Eighteen", "Nineteen"
    };

    // Array to store multiples of ten
    string tens[]
        = { "",      "Twenty",  "Thirty", "Forty", "Fifty",
            "Sixty", "Seventy", "Eighty", "Ninety" };

    // If number is less than 20, return without any further
    // computation
    if (n < 20)
        return (first_twenty[n]);

    // Answer variable to store the conversion
    string answer = "";
    for (long long int i = n; i > 0;
         i %= limit, limit /= 1000) {

        // Store the value in multiplier[t], i.e n =
        // 1000000, then r = 1, for multiplier(million), 0
        // for multipliers(trillion and billion)
        curr_hun = i / limit;

        // It might be possible that the current multiplier
        // is bigger than your number
        while (curr_hun == 0) {

            // Set i as the remainder obtained when n was
            // divided by the limit
            i %= limit;

            // Divide the limit by 1000, shifts the
            // multiplier
            limit /= 1000;

            // Get the current value in hundreds, as
            // English system works in hundreds
            curr_hun = i / limit;

            // Shift the multiplier
            ++t;
        }

        // If current hundred is greater than 99, Add the
        // hundreds' place
        if (curr_hun > 99)
            answer += (first_twenty[curr_hun / 100]
                       + " Hundred ");

        // Bring the current hundred to tens
        curr_hun = curr_hun % 100;

        // If the value in tens belongs to [1,19], add using
        // the first_twenty

        if (curr_hun > 0 && curr_hun < 20)
            answer += (first_twenty[curr_hun] + " ");

        // If curr_hun is now a multiple of 10, but not 0
        // Add the tens' value using the tens array
        else if (curr_hun % 10 == 0 && curr_hun != 0)
            answer += (tens[curr_hun / 10 - 1] + " ");

        // If the value belongs to [21,99], excluding the
        // multiples of 10 Get the ten's place and one's
        // place, and print using the first_twenty array

        else if (curr_hun > 20 && curr_hun < 100)
            answer += (tens[curr_hun / 10 - 1] + " "
                       + first_twenty[curr_hun % 10] + " ");

        // If Multiplier has not become less than 1000,
        // shift it
        if (t < 4)
            answer += (multiplier[++t] + " ");
    }
    return (answer);
}
int main()
{
    long long int n = 36;
    cout << numberToWords(n) << '\n';
    n = 123456789;
    cout << numberToWords(n) << '\n';
    n = 10101010110001;
    cout << numberToWords(n) << '\n';
    n = 999999999;
    cout << numberToWords(n) << '\n';
    return 0;
}
// This Code is contributed by Alok Khansali

Java

public class GFG {
    static String numberToWords(long n)
    {
        long limit = 1000000000000L, curr_hun, t = 0;

        // If zero return zero
        if (n == 0)
            return ("Zero");

        // Array to store the powers of 10
        String multiplier[] = { "", "Trillion", "Billion",
                                "Million", "Thousand" };

        // Array to store numbers till 20
        String first_twenty[] = {
            "",        "One",       "Two",      "Three",
            "Four",    "Five",      "Six",      "Seven",
            "Eight",   "Nine",      "Ten",      "Eleven",
            "Twelve",  "Thirteen",  "Fourteen", "Fifteen",
            "Sixteen", "Seventeen", "Eighteen", "Nineteen"
        };

        // Array to store multiples of ten
        String tens[] = { "",        "Twenty", "Thirty",
                          "Forty",   "Fifty",  "Sixty",
                          "Seventy", "Eighty", "Ninety" };

        // If number is less than 20, return without any
        // further computation
        if (n < 20L)
            return (first_twenty[(int)n]);
        String answer = "";
        for (long i = n; i > 0; i %= limit, limit /= 1000) {

            // Store the value in multiplier[t], i.e n =
            // 1000000, then r = 1, for multiplier(million),
            // 0 for multipliers(trillion and billion)
            // multiplier here refers to the current
            // accessible limit
            curr_hun = i / limit;

            // It might be possible that the current
            // multiplier is bigger than your number
            while (curr_hun == 0) {

                // Set i as the remainder obtained when n
                // was divided by the limit
                i %= limit;

                // Divide the limit by 1000, shifts the
                // multiplier
                limit /= 1000;

                // Get the current value in hundreds, as
                // English system works in hundreds
                curr_hun = i / limit;

                // Shift the multiplier
                ++t;
            }

            // If current hundred is greater than 99, Add
            // the hundreds' place
            if (curr_hun > 99)
                answer += (first_twenty[(int)curr_hun / 100]
                           + " Hundred ");

            // Bring the current hundred to tens
            curr_hun = curr_hun % 100;

            // If the value in tens belongs to [1,19], add
            // using the first_twenty
            if (curr_hun > 0 && curr_hun < 20)
                answer
                    += (first_twenty[(int)curr_hun] + " ");

            // If curr_hun is now a multiple of 10, but not
            // 0 Add the tens' value using the tens array
            else if (curr_hun % 10 == 0 && curr_hun != 0)
                answer
                    += (tens[(int)curr_hun / 10 - 1] + " ");

            // If the value belongs to [21,99], excluding
            // the multiples of 10 Get the ten's place and
            // one's place, and print using the first_twenty
            // array
            else if (curr_hun > 20 && curr_hun < 100)
                answer
                    += (tens[(int)curr_hun / 10 - 1] + " "
                        + first_twenty[(int)curr_hun % 10]
                        + " ");

            // If Multiplier has not become less than 1000,
            // shift it
            if (t < 4)
                answer += (multiplier[(int)++t] + " ");
        }
        return (answer);
    }

    public static void main(String args[])
    {
        long n = 36L;
        System.out.println(numberToWords(n));
        n = 123456789;
        System.out.println(numberToWords(n));
        n = 10101010110001L;
        System.out.println(numberToWords(n));
        n = 999999999;
        System.out.println(numberToWords(n));
    }
}
// This Code is contributed by Alok Khansali

Python

def numberToWords(n):
    limit, t = 1000000000000, 0
    # If zero print zero
    if (n == 0):
        print("zero")
        return

    # Array to store the powers of 10
    multiplier = ["", "Trillion", "Billion", "Million", "Thousand"]

    # Array to store numbers till 20
    first_twenty = ["", "One", "Two",
                    "Three", "Four", "Five",
                    "Six", "Seven", "Eight",
                    "Nine", "Ten", "Eleven",
                    "Twelve", "Thirteen", "Fourteen",
                    "Fifteen", "Sixteen", "Seventeen",
                    "Eighteen", "Nineteen"]

    # Array to store multiples of ten
    tens = ["", "Twenty", "Thirty", "Forty", "Fifty",
            "Sixty", "Seventy", "Eighty", "Ninety"]

    # If number is less than 20, print without any
    if (n < 20):
        print(first_twenty[n])
        return
    answer = ""
    i = n
    while(i > 0):
        '''
        Store the value in multiplier[t], i.e n = 1000000,
        then r = 1, for multiplier(million), 0 for multipliers(trillion and billion)
        multiplier here refers to the current accessible limit
        '''
        curr_hun = i // limit

        # It might be possible that the current multiplier is bigger than your number
        while (curr_hun == 0):

            # Set i as the remainder obtained when n was divided by the limit
            i %= limit

            # Divide the limit by 1000, shifts the multiplier
            limit /= 1000

            # Get the current value in hundreds, as English system works in hundreds
            curr_hun = i // limit

            # Shift the multiplier
            t += 1

        # If current hundred is greater than 99, Add the hundreds' place
        if (curr_hun > 99):
            answer += (first_twenty[curr_hun // 100] + " tensundred ")

        # Bring the current hundred to tens
        curr_hun = curr_hun % 100

        # If the value in tens belongs to [1,19], add using the first_twenty
        if (curr_hun > 0 and curr_hun < 20):
            answer += (first_twenty[curr_hun] + " ")

        # If curr_hun is now a multiple of 10, but not 0
        # Add the tens' value using the tens array
        elif (curr_hun % 10 == 0 and curr_hun != 0):
            answer += (tens[(curr_hun//10) - 1] + " ")

        # If the value belongs to [21,99], excluding the multiples of 10
        # Get the ten's place and one's place, and print using the first_twenty array
        elif (curr_hun > 19 and curr_hun < 100):
            answer += (tens[(curr_hun//10) - 1] + " " +
                       first_twenty[curr_hun % 10] + " ")

        # If Multiplier has not become less than 1000, shift it
        if (t < 4):
            answer += (multiplier[t] + " ")

        i = i % limit
        limit = limit // 1000

    print(answer)


n = 36
numberToWords(n)
n = 123456789
numberToWords(n)
n = 10101010110001
numberToWords(n)
n = 999999999
numberToWords(n)

# This code is contributed by Alok Khansali

C#

// Include namespace system
using System;


public class numtowords
{
    public static String numberToWords(long n)
    {
        var limit = 1000000000000L;
        long curr_hun;
        var t = 0;
        // If zero return zero
        if (n == 0)
        {
            return ("Zero");
        }
        // Array to store the powers of 10
        String[] multiplier = {"", "Trillion", "Billion", "Million", "Thousand"};
        // Array to store numbers till 20
        String[] first_twenty = {"", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};
        // Array to store multiples of ten
        String[] tens = {"", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};
        // If number is less than 20, return without any
        // further computation
        if (n < 20L)
        {
            return (first_twenty[(int)n]);
        }
        var answer = "";
        for (long i = n; i > 0;
        i %= limit,
        limit /= 1000)
        {
            // Store the value in multiplier[t], i.e n =
            // 1000000, then r = 1, for multiplier(million),
            // 0 for multipliers(trillion and billion)
            // multiplier here refers to the current
            // accessible limit
            curr_hun = i / limit;
            // It might be possible that the current
            // multiplier is bigger than your number
            while (curr_hun == 0)
            {
                // Set i as the remainder obtained when n
                // was divided by the limit
                i %= limit;
                // Divide the limit by 1000, shifts the
                // multiplier
                limit /= 1000;
                // Get the current value in hundreds, as
                // English system works in hundreds
                curr_hun = i / limit;
                // Shift the multiplier
                ++t;
            }
            // If current hundred is greater than 99, Add
            // the hundreds' place
            if (curr_hun > 99)
            {
                answer += (first_twenty[(int)((int)curr_hun / 100)] + " Hundred ");
            }
            // Bring the current hundred to tens
            curr_hun = curr_hun % 100;
            // If the value in tens belongs to [1,19], add
            // using the first_twenty
            if (curr_hun > 0 && curr_hun < 20)
            {
                answer += (first_twenty[(int)curr_hun] + " ");
            }
            else if (curr_hun % 10 == 0 && curr_hun != 0)
            {
                answer += (tens[(int)((int)curr_hun / 10) - 1] + " ");
            }
            else if (curr_hun > 20 && curr_hun < 100)
            {
                answer += (tens[(int)((int)curr_hun / 10) - 1] + " " + first_twenty[(int)curr_hun % 10] + " ");
            }
            // If Multiplier has not become less than 1000,
            // shift it
            if (t < 4)
            {
                answer += (multiplier[(int)++t] + " ");
            }
        }
        return (answer);
    }
    public static void Main(String[] args)
    {
        var n = 36L;
        Console.WriteLine(numtowords.numberToWords(n));
        n = 123456789;
        Console.WriteLine(numtowords.numberToWords(n));
        n = 10101010110001L;
        Console.WriteLine(numtowords.numberToWords(n));
        n = 999999999;
        Console.WriteLine(numtowords.numberToWords(n));
    }
}

Javascript

function numberToWords(n)
{
    let limit = 1000000000000, t = 0
    // If zero console.log zero
    if (n == 0)
    {
        console.log("zero")
        return
    }
    // Array to store the powers of 10
    let multiplier = ["", "Trillion", "Billion", "Million", "Thousand"]

    // Array to store numbers till 20
    let first_twenty = ["", "One", "Two",
                    "Three", "Four", "Five",
                    "Six", "Seven", "Eight",
                    "Nine", "Ten", "Eleven",
                    "Twelve", "Thirteen", "Fourteen",
                    "Fifteen", "Sixteen", "Seventeen",
                    "Eighteen", "Nineteen"]

    // Array to store multiples of ten
    let tens = ["", "Twenty", "Thirty", "Forty", "Fifty",
            "Sixty", "Seventy", "Eighty", "Ninety"]

    // If number is less than 20, console.log without any
    if (n < 20)
    {
        console.log(first_twenty[n])
        return
    }
    let answer = ""
    let i = n
    while(i > 0)
    {
        /*
        Store the value in multiplier[t], i.e n = 1000000,
        then r = 1, for multiplier(million), 0 for multipliers(trillion and billion)
        multiplier here refers to the current accessible limit
        */
        let curr_hun = Math.floor(i / limit)

        // It might be possible that the current multiplier is bigger than your number
        while (curr_hun == 0)
        {
            // Set i as the remainder obtained when n was divided by the limit
            i %= limit

            // Divide the limit by 1000, shifts the multiplier
            limit /= 1000

            // Get the current value in hundreds, as English system works in hundreds
            curr_hun = Math.floor(i / limit)

            // Shift the multiplier
            t += 1
        }

        let flr = Math.floor(curr_hun / 100);

        // If current hundred is greater than 99, Add the hundreds' place
        if (curr_hun > 99)
            answer += (first_twenty[flr] + " tensundred ")

        // Bring the current hundred to tens
        curr_hun = curr_hun % 100

        // If the value in tens belongs to [1,19], add using the first_twenty
        if (curr_hun > 0 && curr_hun < 20)
            answer += (first_twenty[curr_hun] + " ")

        // If curr_hun is now a multiple of 10, but not 0
        // Add the tens' value using the tens array
        else if (curr_hun % 10 == 0  &&  curr_hun != 0){
            flr = Math.floor(curr_hun / 10);
            answer += (tens[flr - 1] + " ")
        }

        // If the value belongs to [21,99], excluding the multiples of 10
        // Get the ten's place and one's place, and console.log using the first_twenty array
        else if (curr_hun > 19  &&  curr_hun < 100){
            flr = Math.floor(curr_hun / 10);
            answer += (tens[flr - 1] + " " +
                       first_twenty[curr_hun % 10] + " ")
        }

        // If Multiplier has not become less than 1000, shift it
        if (t < 4)
            answer += (multiplier[t] + " ")

        i = i % limit
        limit = Math.floor(limit / 1000)
    }

    console.log(answer)
}

let n = 36
numberToWords(n)
n = 123456789
numberToWords(n)
n = 10101010110001
numberToWords(n)
n = 999999999
numberToWords(n)

// This code is contributed by phasing17.

Output

Thirty Six 
One Hundred Twenty Three Million Four Hundred Fifty Six Thousand Seven Hundred Eighty Nine 
Ten Trillion One Hundred One Billion Ten Million One Hundred Ten Thousand One 
Nine Hundred Ninety Nine Million Nine Hundred Ninety Nine Thousand Nine Hundred Ninety Nine 

Time Complexity: O(Log₁₀(N))
Auxiliary Space: O(1)