Please help me use c++ language solve this problem

The factorial of a nonnegative integer n is written n! (pronounced "n factorial")* and is defined as follows: n! = n middot (n - 1) middot (n- 2) middot...middot 1 (for values of n greater than 1) and n! = 1 (for n = 0 or n = 1). For example, 5! = 5 middot 4 middot 3 middot 2 middot 1, which is 120. Use while statements in each of the following: a) Write a program that reads a nonnegative integer and computes and prints its factorial. b) Write a program that estimates the value of the mathematical constant e by using the^formula: e = 1 + 1/1! + 1/2! + 1/3! + ... Prompt the user for the desired accuracy of e (i.e., the number of terms in the summation). c) Write a program that computes the value of ex by using the formula e^x = 1 + x/1! + x^2/2! + x^3/3! + ... Prompt the user for the desired accuracy of e (i.e., the number of terms in the summation)