this is my solution and it works

include

using namespace std;

int main() { int a, b, div, rem; cin >> a >> b; int sum = a; while(a >= b) { div = a / b; sum += div; mod = a % b; a = div + rem; } cout << sum << endl; return 0; }

but I saw other people solutions and they have used a formula that calculates answer without any loop

ans = (a * b — 1)/(b — 1)

Can someone please help me how to get this formula?