#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define eb emplace_back
//mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
#define mod 998244353
#define int __int128
#define inf 0x3f3f3f3f
#define INF ((int)1e19)
inline int read()
{
	char ch=getchar(); int nega=1; while(!isdigit(ch)) {if(ch=='-') nega=-1; ch=getchar();}
	int ans=0; while(isdigit(ch)) {ans=ans*10+ch-48;ch=getchar();}
	if(nega==-1) return -ans;
	return ans;
}
void print(vector<int> x){for(int i=0;i<(int)x.size();i++) printf("%d%c",x[i]," \n"[i==(int)x.size()-1]);}
void work()
{
	int n=read(),k=read();
	vector<int> s;
	while(n)
	{
		s.push_back(n%10);
		n/=10;
	}
	while((int)s.size()<36) s.push_back(0);
	int mn=INF;
	if(k==0)
	{
		int pw=1;
		for(int i=0;;i++)
		{
			if(s[i]!=9)
			{
				printf("%lld\n",(long long)pw);
				return ;
			}
			pw*=10;
		}
	}
	for(int c=0;c<=18;c++)
	{
		int ans=0;
		vector<int> ts=s;
		int pw=1;
		for(int i=0;i<c;i++) pw*=10;
		int tk=k;
		for(int i=c;i<(int)ts.size();i++)
		{
			if(tk) ans+=pw*(10-ts[i]),ts[i+1]++,tk--;
			else
			{
				if(ts[i]==10) ans=INF;
				break;
			}
			pw*=10;
		}
		mn=min(mn,ans);
	}
	printf("%lld\n",(long long)mn);
}
signed main()
{
	int T=read(); while(T--) work();
	return 0;
}