#include<bits/stdc++.h>

using namespace std;

#define ll long long

ll t,n,k,m,po[222];

ll getmin(ll x)

{

    ll ret=0,data[55],id=0;

    po[0]=1;

    while(x)

    {

        data[id++]=x;

        x/=10;

        po[id]=po[id-1]*10;

    }

    for(int i=0; i<id; i++)

        ret+=data[i]-po[id-i-1]+1;

    return ret;

}

int main()

{

    scanf("%lld",&t);

    while(t--)

    {

        scanf("%lld%lld",&k,&m);

        m-=getmin(k);

        if(m<0)printf("0\n");

        else if(m==0)printf("%lld\n",k);

        else

        {

            ll hig,big;

            for(ll i=1;; i*=10)

                if(k/i<10)

                {

                    big=i;

                    hig=k-i;

                    break;

                }

            if(big==k)printf("0\n");

            else

            {

                big*=10;

                hig*=10;

                while(m>hig)

                {

                    m-=hig;

                    hig*=10;

                    big*=10;

                }

                printf("%lld\n",big+m-1);

            }

        }

    }

    return 0;

}