Largest K digit number divisible by X in C++

In this tutorial, we are going to write a program that finds the largest k-digit number that is divisible by x.

Let's see the steps to solve the problem.

Initialise the x and k.
Find the value of pow(10, k) - 1 which is largest k-digit number.
Now, remove the remainder value from the above value to get the largest k-digit number that is divisible by x.

Example

Let's see the code.

#include <bits/stdc++.h>
using namespace std;
int answer(int x, int k) {
   int max = pow(10, k) - 1;
   return max - (max % x);
}
int main() {
   int x = 45, k = 7;
   cout << answer(x, k) << endl;
   return 0;
}