Question

1. Write a python program to compute the factorial of a given non-negative integer n. If the user inputs any integer outside the required, print “Error! Try again!”

Answer 1

I have provided the required code below.

All the steps have been explained via the comments, however, please ask in the comments if you need any clarifications. Thank you.

THE CODE:

def fact(n):

    #function to recurisively calculate the factorial of a number

    if (n==1 or n==0):

        #return 1 if factorial of 0 or 1 is needed

        return 1

    else:

        #recursively calls the factorial function

        return(n * fact(n - 1))

#takes input from the user

num = int(input('Enter a non-negative number: '))

#checks whether the input is non-negative

#if yes, prints "Error! Try again. " and queries for a new number until a postive one is provided.

if(num < 0):

    while(num<0):

        print("Error! Try again. ")

        num = int(input('Enter a non-negative number: '))

#prints the final result

print("Factorial of " + str(num) + " is " +  str(fact(num)))

CODE SCREENSHOT:

CODE OUTPUT:

NOTE: Please look at the code screenshot to understand the indentation in a better way.