#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
int T,k;
ull n;
const int maxn=30+5;
int cnt,a[maxn];
ull dp[20][20][2];
bool vis[20][20][2];
const ull Inf=0x3f3f3f3f3f3f3f3f;
ull tmp[20];
ull dfs(int p,int sum,int flag) {
	if(vis[p][sum][flag]) return dp[p][sum][flag];
	vis[p][sum][flag]=1;
	if(!sum) {
		if(!flag) return dp[p][sum][flag]=0;
		else if(flag&&a[p]!=0) return dp[p][sum][flag]=tmp[p-1]*(10-a[p]);
		else return dp[p][sum][flag]=Inf;
	} 
	if(p==1) {
		if(!sum) {
			if(flag==1&&a[1]!=0) return dp[p][sum][flag]=10-a[1];
			else if(flag==0) return dp[p][sum][flag]=0;
		}
		return dp[p][sum][flag]=Inf;
	}
	ull res=Inf;
	int op=10-a[p];
	if(flag) {
		if(sum) res=min(res,tmp[p-1]*(op-1)+dfs(p-1,sum-1,1));
		if(op!=10) res=min(res,tmp[p-1]*op+dfs(p-1,sum,0));
	}
	else {
		if(op!=1) res=min(res,dfs(p-1,sum-1,1));
		res=min(res,dfs(p-1,sum,0));
	}
	return dp[p][sum][flag]=res;
}
void solve() {
	ull x=n;
	cnt=0;
	while(x) {
		a[++cnt]=x%10;
		x/=10;
	}
	if(!k) {
		for(int i=1;i<=19;++i)
			if(a[i]<9) {
				printf("%llu\n",tmp[i-1]);
				return;
			}
	}
	int p=1;
	while(a[p]==0) p++;
	for(int i=p;i<=cnt;++i) a[i-p+1]=a[i];
	for(int i=cnt-p+2;i<=k;++i) a[i]=0;
	memset(vis,0,sizeof(vis));
	int tmp=max(cnt,k)+1;
	dfs(tmp,k,0);
	if(k) dfs(tmp,k-1,1);
	ull ans=min(dp[tmp][k][0],dp[tmp][k-1][1]);
	if(ans==Inf) puts("-1");
	else {
		printf("%llu",ans);
		for(int i=1;i<p;++i) printf("0");
		puts("");
	}
}
void Init() {
	tmp[0]=1;
	for(int i=1;i<=19;++i) tmp[i]=tmp[i-1]*10;
}
int main() {
	Init();
	scanf("%d",&T);
	while(T--) {
		scanf("%llu%d",&n,&k);
		solve();
	}
	return 0;
}