[Druchii]

Got this so far, it appears to work...

Spoiler: 

//c++
#include <iostream>
using namespace std;

int main() {
float interest;
float mortgage=100000;
float repayment;
long i=1;
cout << "Please enter the interest rate in number format sans % mark.\n";
cin >> interest;
cout << "Ok, Interest rate is set to " << interest << "% \nPlease enter the Mortgage payback amount per month sans delimiters.\n";
cin >> repayment;
do {
mortgage = mortgage - repayment;
if (i % 12 == 0){
mortgage = mortgage*(1+(interest/100));
}
++i;
} while (mortgage > 0);
cout << "100,000 repaid at " << repayment << " per month would take " << i << " months to pay off";
}