#include<bits/stdc++.h>
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
#define endl '\n'
#define ll long long int
#define vi vector<int> 
#define mx(a,b,c,d) max(a, max(b, max(c,d)))
#define MP make_pair
#define pb push_back
#define ppb pop_back
const int md = 1e9 + 7;

const ll INF=1e9+15;
const ll NAX= 2e5+5; // change it acc tothe contraints
 

void solve()
{
    ll n;
    cin>>n;
    ll num;
    cin>>num;
    ll new_num=num;
    vector<ll> arr;

    while(num!=0){
        ll temp=num%10;
        arr.pb(temp);
        num/=10;
        break;
    }
 //   debug(arr);
    vector<string>numbers;
    string str_9=" ";
    for(int i=0; i<n; i++){
        numbers.pb("9");
        str_9+=numbers[i];
        //debug(arr,str_9, numbers);
    }
    ll num_9=stoll(str_9);
    if(arr[0]!=9){
        cout<<num_9-new_num<<endl;;
        return;
    }
    else{
        numbers.clear();
        string str_1=" ";
        ll num_1;
        for(int i=0; i<n-1; i++){
            numbers.pb("1");
            str_1+=numbers[i];
        }
        str_1+="2";
        num_1=stoll(str_1);
        cout<<num_1<<endl;
        //debug(str_1, num_1, numbers);
        return;
    
    }

}
int main() {
		
     ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

int tc=1;
    cin>>tc;
    for (int i=0; i<tc; i++){
		solve();
		//cerr << "time taken : " << (float)clock() / CLOCKS_PER_SEC << " secs" << endl;

		}
		


}