Before going to the program first let us understand what is a *Factorial of a Number?*

**Factorial of a Number:**

The *factorial of a Number* *n*, denoted by *n*! , is the product of all positive integers less than or equal to *n*.

The value of 0! is 1 according to the convention for an empty product.

For example,

4! = 4 * 3 * 2 * 1 = 24

## Program code for Factorial of a Number in C++:

#include<iostream.h> #include<conio.h> void main() { int n,i,f=1; clrscr(); cout<<" Enter The Number:"; cin>>n; //LOOP TO CALCULATE THE FACTORIAL OF A NUMBER for(i=1;i<=n;i++) { f=f*i; } cout" The Factorial of "<<n<<" is "<<f; getch(); }

**Related: **Factorial of a Number in C using For Loop

## Working:

- First the computer reads the number to find the factorial of the number from the user.
- Then using for loop the value of ‘i’ is multiplied with the value of ‘f’.
- The loop continues till the value of ‘n’.Finally the factorial value of the given number is printed.

## Step by Step working of the above Program Code:

Let us assume that the number entered by the user is **4**.

- It assigns the value of n=4 , i=1 , f=1
- Then the loop continues till the condition of the for loop is true.

2.1. i<=n (1<=4) , for loop condition is true.

f=f*i (f=1*1) So f=1

i++ (i=i+1) So i=2

2.2. i<=n (2<=4) , for loop condition is true.

f=f*i (f=1*2) So f=2

i++ (i=i+1) So i=3

2.3. i<=n (3<=4) , for loop condition is true.

f=f*i (f=2*3) So f=6

i++ (i=i+1) So i=4

2.4. i<=n (4<=4) , for loop condition is true.

f=f*i (f=6*4) So f=24

i++ (i=i+1) So i=5

2.5. i<=n (5<=4) , for loop condition is true.

It comes out of the for loop.

- Finally it prints as given below

The Factorial of 4 is 24

- Thus the program execution is completed.