sumToGrnKop

#include <iostream>

int main()
{
    const int kopInGrn{ 100 };
    double sum{64.70};
    int grn;
    int kop;

    std::cout << "Enter the summ: ";
    std::cin >> sum;

    // Variant A - simpler to understand how it works
    //kop = sum * kopInGrn;
    //grn = kop / kopInGrn;
    //kop %= kopInGrn;

    // Variant B - shorter :)
    grn = sum;
    kop = (sum - grn) * kopInGrn;

    std::cout << "The summ is equal: " << grn << " grn. " << kop << " kop.\n";

    return 0;
}