Smallest N digit number which is a multiple of 5

Given an integer N ≥ 1, the task is to find the smallest N digit number which is a multiple of 5.

Examples:

Input: N = 1
Output: 5

Input: N = 2
Output: 10

Input: N = 3
Output: 100



Approach:

  • If N = 1 then the answer will be 5.
  • If N > 1 then the answer will be (10(N – 1)) because the series of smallest multiple of 5 will go on like 10, 100, 1000, 10000, 100000, …

Below is the implementation of the above approach:

C++

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// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the smallest n digit
// number which is a multiple of 5
int smallestMultiple(int n)
{
    if (n == 1)
        return 5;
    return pow(10, n - 1);
}
  
// Driver code
int main()
{
    int n = 4;
    cout << smallestMultiple(n);
  
    return 0;
}

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Java

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// Java implementation of the approach
class GFG {
  
    // Function to return the smallest n digit
    // number which is a multiple of 5
    static int smallestMultiple(int n)
    {
        if (n == 1)
            return 5;
        return (int)(Math.pow(10, n - 1));
    }
  
    // Driver code
    public static void main(String args[])
    {
        int n = 4;
        System.out.println(smallestMultiple(n));
    }
}

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Python3

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# Python3 implementation of the approach
  
# Function to return the smallest n digit 
# number which is a multiple of 5
def smallestMultiple(n):
  
    if (n == 1):
        return 5
    return pow(10, n - 1)
  
# Driver code
n = 4
print(smallestMultiple(n))

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C#

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// C# implementation of the approach
using System;
class GFG {
  
    // Function to return the smallest n digit
    // number which is a multiple of 5
    static int smallestMultiple(int n)
    {
        if (n == 1)
            return 5;
        return (int)(Math.Pow(10, n - 1));
    }
  
    // Driver code
    public static void Main()
    {
        int n = 4;
        Console.Write(smallestMultiple(n));
    }
}

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PHP

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<?php
// PHP implementation of the approach
  
// Function to return the smallest n digit 
// number which is a multiple of 5
function smallestMultiple($n)
{
    if ($n == 1)
        return 5;
    return pow(10, $n - 1);
}
  
// Driver code
$n = 4;
echo smallestMultiple($n);
?>

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Output:

1000

Time Complexity: O(1)



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