#define _CRT_SECURE_NO_WARNINGS
#include<queue>
#include<cmath>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;

using namespace std;
typedef unsigned long long ull;
const int N=30;
int n,cnt,K,c[N];
ull x,base[N];
char s[N];

inline void sol()
{
    cnt=0;
    scanf("%llu%d",&x,&K);
    ull tem=x;
    while(tem)
    {
        c[++cnt]=tem%10;
        tem/=10;
    }
    n=cnt;
    if(K>=n)
    {
        ull ans=base[K];
        printf("%llu\n",ans-x);
        return;
    }
    int pos;
    for(int i=K+1;i<=n+1;i++)
        if(c[i]<9){ pos=i;break; }
    ull ans=0;
    if(!K)ans=base[pos-1];
    else
        for(int i=pos-1;i>=pos-K;i--)
            ans+=((i==pos-K)?10-c[i]:9-c[i])*base[i-1];
    printf("%llu\n",ans);
}

signed main()
{
    int T;
    base[0]=1;
    for(int i=1;i<=18;i++)
        base[i]=base[i-1]*10ull;
    scanf("%d",&T);
    while(T--)
        sol();
    return 0;
}