Largest K digit number divisible by X

Integers X and K are given. The task is to find the highest K-digit number divisible by X.

Examples:

Input : X = 30, K = 3
Output : 990
990 is the largest three digit 
number divisible by 30.

Input : X = 7, K = 2
Output : 98

A simple solution is to try all numbers starting from the largest K digit number (which is 999…K-times) and return the first number divisible by X.

An efficient solution is to use below formula. 

ans = MAX - (MAX % X)
where MAX is the largest K digit 
number which is  999...K-times

The formula works on simple school method division. We remove remainder to get the largest divisible number.

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP code to find highest K-digit number divisible by X
#include <bits/stdc++.h>
using namespace std;
  
// Function to compute the result
int answer(int X, int K)
{
    // Computing MAX
    int MAX = pow(10, K) - 1;
  
    // returning ans
    return (MAX - (MAX % X));
}
  
// Driver
int main()
{
    // Number whose divisible is to be found
    int X = 30;
  
    // Max K-digit divisible is to be found
    int K = 3;
  
    cout << answer(X, K);
}

chevron_right






                        filter_none









Java














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// Java code to find highest 


// K-digit number divisible by X 


  


import java.io.*; 


import java.lang.*; 


  


class GFG { 


    public static double answer(double X, double K) 


    { 


        double i = 10; 


        // Computing MAX 


        double MAX = Math.pow(i, K) - 1; 


  


        // returning ans 


        return (MAX - (MAX % X)); 


    } 


  


    public static void main(String[] args) 


    { 


  


        // Number whose divisible is to be found 


        double X = 30; 


  


        // Max K-digit divisible is to be found 


        double K = 3; 


  


        System.out.println((int)answer(X, K)); 


    } 


} 


  


// Code contributed by Mohit Gupta_OMG <(0_o)> 



















                        chevron_right







                        filter_none









Python3














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















# Python code to find highest  


# K-digit number divisible by X 


  


def answer(X, K): 


      


    # Computing MAX 


    MAX = pow(10, K) - 1


      


    # returning ans 


    return (MAX - (MAX % X)) 


  


X = 30;  


K = 3;  


  


print(answer(X, K));  


  


# Code contributed by Mohit Gupta_OMG <(0_o)> 



















                        chevron_right







                        filter_none









C#














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// C# code to find highest 


// K-digit number divisible by X 


  


using System; 


  


class GFG { 


      


    public static double answer(double X, double K) 


    { 


          


        double i = 10; 


          


        // Computing MAX 


        double MAX = Math.Pow(i, K) - 1; 


  


        // returning ans 


        return (MAX - (MAX % X)); 


    } 


  


    public static void Main() 


    { 


  


        // Number whose divisible is to be found 


        double X = 30; 


  


        // Max K-digit divisible is to be found 


        double K = 3; 


  


        Console.WriteLine((int)answer(X, K)); 


    } 


} 


  


// This code is contributed by vt_m. 



















                        chevron_right







                        filter_none









PHP














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















<?php 


// PHP code to find highest K-digit 


// number divisible by X 


  


// Function to compute the result 


function answer($X, $K) 


{ 


      


    // Computing MAX 


    $MAX = pow(10, $K) - 1; 


  


    // returning ans 


    return ($MAX - ($MAX % $X)); 


} 


  


// Driver 


    // Number whose divisible 


    // is to be found 


    $X = 30; 


  


    // Max K-digit divisible 


    // is to be found 


    $K = 3; 


  


    echo answer($X, $K); 


  


// This code is contributed by ajit 


?> 



















                        chevron_right







                        filter_none










Output:


990



This article is contributed by Rohit Thapliyal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.


Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



          
          
          
          

            

    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:

Improved By :  vt_m, jit_t, Akanksha_Rai