Hello here is my factorial program I wrote in Python
def fact (n): if n == 0: return 1
return n*fact(n - 1);
number = int(raw_input("Enter a number:"))
if number < 0: print "No"
else: print fact(number)
import operator
def fact(x): return reduce(operator.mul, xrange(2, x+1))
fact(1)