### C program to find factorial of a number using recursion :

In this tutorial, we will learn how to find the factorial of a number in *c programming language* using *recursion*. *Recursion* means the function will call itself. For example, the factorial of *5* is *5 * 4 * 3 * 2 * 1*. We will call send this number to a function. It will call itself with *5 – 1 =4* and multiply it with *5*. The inner function again call itself etc. It will be more meaningful if I will explain you with an example. Let’s take a look into the program first :

### C program :

#include //4 int factorial(int n){ //5 if(n == 1) return 1; else return (n * factorial(n - 1)); //6 } int main(){ //1 int no; //2 printf("Enter a number : "); scanf("%d",&no); //3 int fact = factorial(no); //7 printf("Factorial of %d is %d \n",no,fact); }

### Explanation :

*The numbers above defines the steps below :*

1. Create one variable *no*.

2. Take the number as input from the user and save it in *no*.

3. Now calculate the factorial. It calls *int factorial(int n)* method to find the *factorial value*. This function takes one int as input and returns one *integer*.

4. For example, if we want to find the factorial of *4*,

– first function *factorial* will be called with *4* as input.

– First function will return *4 * fact(3)*

– *fact(3)* returns *3 * fact(2)*

– *fact(2)* returns *2 * fact(1)</>
– fact(1) returns 1 becase we have the if statement at first to return 1 if n == 1.*

That means, first function will return *4 * fact(3)* = *4 * 3 * fact(2)* = *4 * 3 * 2 * fact(1)* = *4 * 3 * 2 * 1* = 24 . Which is the factorial of *4*

5. Finally, print out the result.

### Sample output :

Enter a number : 10 Factorial of 10 is 3628800 Enter a number : 1 Factorial of 1 is 1 Enter a number : 2 Factorial of 2 is 2 Enter a number : 5 Factorial of 5 is 120