Chapter 4, Problem 4.35E

(Factorial) The factorial of a nonnegative integer n is written n! (pronounced “n factorial”) and is defined as follows:
 n! = n.(n-1)·(n-2)·…·1 (for values of n greater than 1)
and
 n! = 1 (for n = 0 or n = 1).
For Example. 5! = 5·4·3·2·1, which is 120. Use while statement in each of the following:

1. Write a program that reads a nonnegative integer and computes and prints its factorial.
2. Write a program that estimates the value of the mathematical constant e by using the formula: