func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     long long q;     cin >> q;     while (q--) {       long long n, m;       cin >> n;       cin >> m;       if (m > n || m % 10 == 0) {         cout << 0 <<   n ;         continue;       }       long long p = (n / m) / 10;       long long q = (n / m) % 10;       long long sum = 0;       if (m % 2 == 0)         sum = p * (40LL);       else if (m % 5 == 0)         sum = p * (25LL);       else         sum = p * (45LL);       long long num = 0;       for (long long i = 1; i <= q; i++) {         num += m;         sum += (num % 10);       }       cout << sum <<   n ;     }     return 0;   }   