In mathematics, the notation n! represents the factorial of the nonnegative integer n. The factorial of n is the product of all the nonnegative integers from 1 to n. For example: 7! = 1 x 2 x 3 x 4 x 5 x 6 x 7 = 5,040 Write a program that lets the user enter a nonnegative integer and then uses a loop to calculate the factorial of that number. Print the factorial to standard output.

The program to this question can be given as:

Program:

factorial=1 #declare a variable.

number=int (input ("Enter a positive integer:")) #input a number.

while (number>0) : #loop

factorial = factorial*number # holding value in factorial variable

number=number-1

print ('=', factorial) #print value.

Output:

Enter a positive integer:6

= 720

Explanation:

The description of the above python program can be given as:

In the above program firstly we define a variable that is "factorial". In this variable, we assign a value that is 1 and it is used to calculate the factorial value. We define a variable "number". The number variable is used to take input from the user. Then we define a loop in the loop we calculate the factorial and hold the value in the factorial value in the last we print the value.