you could try this and you won't need floats (unless you got .5 in a score):

#include <iostream>

Code:
using namespace std;

int main()
{
    int total;
    int score;
    int percent;

    cout<<"What is the total score? ";
    cin>> total;

    cout<<"What is your score? ";
    cin>> score;

    percent = ( score*100 ) / total;
    cout<<"Your percentage mark is: "<< percent <<"\n";

	return 0;
}