Programming Exercise 4-12
# Inititalize number to zero.
number = 0
# Get a valid number from the user.
while number <= 0:
number = int(input('Enter a nonnegative integer: '))
# Initialize the accumulator variable.
factoral = 1
# Calculate the factoral of the number.
for factor in range(1, number + 1):
factoral *= factor
# Display the factoral of the number.
print('The factoral of', number, 'is', factoral)