A_Divisibility_Problem.cpp

#include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    cin >> n;
    while(n--){
        int a, b;
        cin >> a >> b;
        if(a%b==0){
            cout << 0 << endl;
        }
        else{
            cout << b-(a%b) << endl;
        }
    }
    return 0;
}