#include<bits/stdc++.h>
using namespace std;
#define int long long 
#define rint int
#define endl '\n'
#define uint unsigned long long
void debug(int *a,int n){for(rint i=1;i<=n;i++) cout<<a[i]<<" ";cout<<endl;}
void debug(int *a){for(rint i=1;a[i];i++) cout<<a[i]<<" ";cout<<endl;}
void debug(int x){cout<<"debug: "<<x<<endl;}
int read(){
    int x=0,f=1;char c=getchar();
    while(!isdigit(c)){if(c=='-')f=-1;c=getchar();}
    while(isdigit(c))x=x*10+c-48,c=getchar();
    return x*f;
}const int N=2e5+10,p=1e9,mod=998244353;

int n,m,mm;
char s[N],g[15];
char ans[N],res[N];

bool cmp()
{
	if(!ans[1]) return 1;
	if(res[0]==49) return 0;
	for(rint i=1;i<=n;i++)
	if(ans[i]<res[i]) return 0;
	else if(ans[i]>res[i]) return 1;
	return 0;
}


bool check(int x)
{
	for(rint i=x;i<=x+m-1;i++)
	if(s[i]>g[i-x+1]) return 0;
	else if(s[i]<g[i-x+1]) return 1;
	return 0;
}

void work2(int x)
{
	for(rint i=1;i<x;i++) res[i]=s[i];
	for(rint i=x;i<=x+m-1;i++) res[i]=g[i-x+1];
	for(rint i=x+m;i<=n;i++) res[i]='0';
	
	if(cmp()) 
	for(rint i=1;i<=n;i++) ans[i]=res[i];
}

void baoli()
{
	int nn=0;
	for(rint i=1;i<=n;i++)
		nn=nn*10+s[i]-48;
	if(nn<mm) return cout<<mm<<endl,void();
	
	for(rint i=n-m+1;i>0&&i>=n-m+1-20;i--)
	if(check(i)) work2(i);
	
	int yu=nn%mm;
	yu=mm-yu;
	
	int val=nn+yu;
	
	// cout<<"val "<<val<<endl;
	
	if(ans[1]) 
	{
		int aas=0;
		for(rint i=1;i<=n;i++)
			aas=aas*10+ans[i]-48;
		val=min(val,aas);
	}
	cout<<val<<endl;
}

void work(int yu)
{
	for(rint i=n;~i;i--)
	{
		int x=s[i]-48+yu%10;yu/=10;
		if(x>9) yu++,x-=10;
		res[i]=x+48;
	}
	
	if(cmp()) 
	for(rint i=0;i<=n;i++) ans[i]=res[i];
}

void Work()
{
	ans[1]=0,mm=0,s[0]='0';
	scanf("%s",s+1),n=strlen(s+1);ans[n+1]=0;
	scanf("%s",g+1),m=strlen(g+1);
	for(rint i=1;i<=m;i++) mm=mm*10+g[i]-48;
	
	if(n<=17) return baoli(),void();
	
	for(rint i=n-m+1;i>0&&i>=n-m+1-20;i--)
	if(check(i)) work2(i);
	
	int yu=0;
	for(rint i=1;i<=n;i++)
		yu=(yu*10+s[i]-48)%mm;
	yu=mm-yu;
	
	work(yu);
	
	if(ans[0]==49) putchar('1'),ans[0]=0;
	printf("%s\n",ans+1);
}

signed main()
{
    #ifndef ONLINE_JUDGE
	// freopen("1.in", "r", stdin);
	// freopen("1.out", "w", stdout);
	#else
	#endif
    
	// int T=1;
	int T=read();
	while(T--) Work();
	
    return 0;
}