Factorial of an input number

Script

#!/usr/local/bin/python3.1
import time

n = int(input("Enter the number for which you need to calculate the factorial: "))
r = 1

while n > 0:
        r = r * n
        n = n - 1

print("Please give me a few seconds to calculate................")
print()
time.sleep(3)

print("The factorial of ", n, " is: ", r)
print()

Execution

Enter the number for which you need to calculate the factorial: 10

Please give me a few seconds to calculate................

The factorial of  0  is:  3628800

Enter the number for which you need to calculate the factorial: 5

Please give me a few seconds to calculate................

The factorial of  0  is:  120

Enter the number for which you need to calculate the factorial: 25

Please give me a few seconds to calculate................

The factorial of  0  is:  15511210043330985984000000