### What is Factorial of a Number?

A mathematics term for a non-negative integer n, denoted by n!, which is the product of all positive integers less than or equal to n.e.g-

**4! = 4x3x2x1 = 24**

**So finding factorial of a number is a must have feature if you are willing to build a basic scientific calculator in any programming language. Here we are building factorial program in C but you can also check: Java Program To Find Factorial of Given Number .**

**Different Methods for finding Factorial of a Number in Programming:**

**1.**Using standard for/while loop

**2.**Using loop in a user defined function

*(mostly used)*

**3.**Using recursion

*(best method)*

####
**Factorial Program in C : Using loop**

This is the most common and standard method for finding factorial of a number.

**Source Code:**

#include <stdio.h> #include <conio.h> void main(){ int num ,i,fac=1;; printf("Enter a Number: "); scanf("%d",&num); for(i=num;i>0;i--){ fac = fac*i; } printf("Factorial of %d is: %d ",num,fac); getch(); }

####
**Factorial Program in C : Using User Defined Function**

This method is mostly used because building methods are always best practice to reduce the size and complexity of your code.

**Source Code:**

#include <stdio.h> #include <conio.h> void main(){ int num; printf("Enter a Number: "); scanf("%d",&num); printf("Factorial of %d is: %d ",num,factorial(num)); getch(); } int factorial(int n){ int i,fac=1; for(i=n;i>0;i--){ fac = fac*i; } }

#### Factorial Program in C : Using Recursion

The most important method which every student must know to find factorial of a number using any programming language is using a recursive function (Functions are recursive if they call themselves) lets understand this method from the program given below.

#include <stdio.h> #include <conio.h> void main(){ int num; printf("Enter a Number: "); scanf("%d",&num); printf("Factorial of %d is: %d ",num,factorial(num)); getch(); } int factorial(int n){ if (n<1) return 1; else return n*factorial(n-1); }

**Output:**

So finally you learned all the three methods to build a factorial program in C.

**Also Read:**C Program for Palindrome

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