'''
Purpose: compute n factorial for a user supplied n
'''

# n factorial is the product of numbers from 1 to n

reply = input( 'Enter a number: ' )

n = int( reply )

# want to accumulate the product
# initialize accumulator before the loop
product = 1

# want to accumulate factors 1 through n
# i takes on a new value every time we iterate through the for loop.
# i takes on every value in the range ( including the first value,
#   not including the end value)
for i in range( 1, n + 1 ):
    product = product * i
    print( i, product )

    print() ; input( 'Enter when ready: ' ) ; print

print( product )