If n is odd, then use (n!)/(n-1)!!. If n is even, use (n/2)!*2n/2 More on reddit.com

Man, that's impressive. More on reddit.com

Figuring out a factorial with a while loop is rather trivial. Part of your problem comes from your use of addition rather than multiplication. You could use addition in another loop to calculate factorial, but easier to multiply. Start with a number and a total. Multiple that number by one and store as the total. Lower the number by one. Multiple that new number by the prior calculated total. Repeat until the number equals one. The total is the factorial of the original number. . starting_number = int(input('Number? ')) number = starting_number total = 1 while number > 1: total *= number # multiple the total by the number (5, then 4, then 3...) number -= 1 # reduce the number by one print('{}! equals {}'.format(starting_number, total)) Yields: $ python3 factorial_sorta.py Number? 5 5! equals 120 More on reddit.com

54! / 49! would get you what you're after. In general, if you want to know n * (n-1) * * * (n-k), that will be n! / (n-k-1)! More on reddit.com