factorialL

Find the factorial of a given number

long long factorial(n);

will return the factorial of a given number. There is no custom return type, the function always returns an integer.

factorialL(5); //120
factorialL(0); //1

After n = 20, the function doesn't work anymore, as the numbers are too large for the integer sizing. Yeah, ..., long long allows you to store 1 more n than int, xD. This just tells you how big these numbers can become with increasing n.