1328A. Divisibility Problem.cpp

/*
problem link: https://codeforces.com/problemset/problem/1328/A
problem name:1328A. Divisibility Problem
status:ACCEPTED
author :Mohand Sakr.
*/





#include <iostream>
using namespace std;

int main() {

int t;
cin>>t;

while(t--){
	
	int x,y;
	cin>>x>>y;
	
	if(x%y==0) 
	{
	cout<<0<<endl;
	}
	else {
	
	int w=x%y;
	
	cout<<y-w<<endl;
	
	}
}


	return 0;
}