Divisibility.cpp

/*Divisibility Problem
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
You are given two positive integers a and b. In one move you can increase a by 1 (replace a with a+1). Your task is to find the minimum number of moves you need to do in order to make a divisible by b. It is possible, that you have to make 0 moves, as a is already divisible by b. You have to answer t independent test cases.

Input
The first line of the input contains one integer t (1≤t≤104) — the number of test cases. Then t test cases follow.

The only line of the test case contains two integers a and b (1≤a,b≤109).

Output
For each test case print the answer — the minimum number of moves you need to do in order to make a divisible by b.

Example
inputCopy
5
10 4
13 9
100 13
123 456
92 46
outputCopy
2
5
4
333
0
*/
#include <bits/stdc++.h>
using namespace std;

int main(){
	int a,b,c;
	cin>>c;
	for(int i=0;i<c;i++){
		cin>>a>>b;
		int r=a%b;
		if(r==0){
			cout<<"0"<<endl;
		}
		else{
			cout<<b-r<<endl;
		}
	}
	return 0;
}