#include<bits/stdc++.h>
using namespace std;
long long inf=2e18;
long long f[21][10][21][2];
int zan[21];
int main(){
	int T;
	scanf("%d",&T);
	while(T--){
		long long n;
		int tot=0,K;
		scanf("%lld%d",&n,&K);
		for(int i=1;i<=20;i++)zan[i]=0;		
		while(n)zan[++tot]=n%10,n/=10;
		for(int i=0;i<=20;i++)
			for(int j=0;j<=9;j++)
				for(int k=0;k<=20;k++)
					f[i][j][k][0]=f[i][j][k][1]=inf;
		f[0][0][0][0]=0;
		long long ww=1,minn=inf;
		for(int i=1;i<=18;i++,ww*=10){
			for(int j=0;j<=9;j++){
				for(int k=0;k<=K;k++){
					for(int k2=0;k2<=1;k2++)
						if(f[i-1][j][k][k2]<inf){
							for(int k3=0;k3<=9;k3++){
								int op=k3+j+zan[i];
								int jj=(op/10),kk=(op>=10);
								if(k+kk<=K){
									f[i][jj][kk+k][k2|(k3>0)]=min(f[i][jj][kk+k][k2|(k3>0)],f[i-1][j][k][k2]+k3*ww);
								}		
							}
						}
				}
			}
		}
		for(int i=1;i<=18;i++){
			if(f[i][0][K][1]<inf)
				minn=min(minn,f[i][0][K][1]);
			if(zan[i+1]==0){
				for(int j=0;j<=9;j++)
					minn=min(minn,f[i][j][K][1]);
			}
		}
		if(minn>=inf)printf("-1\n");
		else printf("%lld\n",minn);
	}
}