Factorial of a number (n!):How to Print a FACTORIAL in c program first you have to know what is a FACTORIAL? To Print a FACTORIAL you have to clear your logic.Lets begin,

 

What is factorial of a number?

  • Factorial is denoted by the symbol ‘!’. For example, factorial of a number 10 is denoted as 10!. Factorial of a number is defined as the product of “the number and all integers less than that number except zero and negative integers”.

  • Natural numbers ( non-negative integers ) which are greater than zero are used for factorial concept.

Factorial Example:

Zero factorial (0!) = 1
one factorial (1!) = 1
Two factorial (2!) = 2*1 = 2
Three factorial (3!) = 3*2*1 = 6
Four factorial (4!) = 4*3*2*1 = 24
Five factorial (5!) = 5*4*3*2*1 = 120
etc…

The common mathematical formula for finding factorial of the number ‘n’ is given below.

n! = n ( n – 1)( n – 2)( n – 3) …… (1)

C Program to Print FACTORIAL:

#include <stdio.h>
int main()
{
   int i,fact=1,n;
   printf("\nPlease enter a number to find factorial : ");
   scanf("%d",&n);

   if (n<0)
   {
      printf("\nPlease enter a positive number to find factorial and try again.Factorial can't be found for negative values. It can be only positive or 0 \n");
      return 1;
   }

   for(i=1;i<=n;i++)
   fact=fact*i;
   printf("Entered number is %d and it's factorial is %d! = %d\n",n,n,fact);
   return 0;
}

OUTPUT:

Please enter a number to find factorial :5
Entered number is 5 and it’s factorial is 5! = 120