Here.... look at the difference, and *think about it*, I think you'll figure it out
Code:

# include <iostream>
# include <cmath>
using namespace std;
int average, sd, s1, s2, s3, s4, deviation;
int main()
{
cout << "Press enter after entering a value.\n";
cout << endl;
cout << "Enter score one: ";
cin >> s1;
cout << "\nEnter score two: ";
cin >> s2;
cout << "\nEnter score three: ";
cin >> s3;
cout << "\nEnter score four: ";
cin >> s4;
average =(s1+s2+s3+s4)/4;
deviation =(((s1-average)*(s1-average))+((s2-average)*(s2-average))+((s3-average)*(s3-average))+((s4-average)*(s4-average)))/3;
sd = sqrt(deviation);
cout << "\nThe average of your four scores is "<<average<<".\n";
cout << "The stand deviation of your scores is "<<sd<<".\n";
return 0;
}