Here's a C program to find the factorial of a given number using For loop with output and proper explanation.

What is Factorial?The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. The factorial of 0 and 1 is 1.

# include <stdio.h> # include <conio.h> void main() { long n, i, f = 1 ; clrscr() ; printf("Enter a number : ") ; scanf("%ld", &n) ; for(i = 2 ; i <= n ; i++) f = f * i ; printf("\nFactorial value of %ld is : %ld", n, f) ; getch() ; }

**Output of above program is**

Enter a number : 5

Factorial value of 5 is : 120

**Explanation of above program**

There are three variables in this program all of type long -

- n - is the number whose factorial we're calculating.
- f - is the factorial of n. It is initialized to 1 at the start of the program.
- i - is the loop variable.

First we ask the user to enter a number. Then we calculate the factorial of that number using a for loop. Our for loop runs for the value of loop variable i = 2 to n. Inside the for loop we simply multiply each value of loop variable with previously calculated factorial value (f) and again storing it in the same

**f**variable for further calculations.
Suppose, n = 5. So our for loop will run for the value of i = 2, 3, 4 and 5 -

**i = 2, f = 1 -**This is the first iteration. Inside the loop the value of f is updated as - f = f * i. So f = 1 * 2 = 2.**i = 3, f = 2**- The new value of f = f * i = 2 * 3 = 6.**i = 4, f = 6**- The new value of f = f * i = 6 * 4 = 24.**i = 5, f = 24**- The new value of f = f * i = 24 * 5 = 120.

Tip:We could have run our for loop from i = 1 to n but by doing this we're just wasting one looping cycle and hence the resources because in the first iteration if the value of i = 1 and f = 1 then again f = 1 * 1 = 1. As there is no change in the value of f we can eliminate this step. Hence we're using our loop from i = 2 to n.

. We introduce a sequence of integers 0 - end of the sequence. Whether a sequence contains at least three negative numbers. Calculate the sum of odd numbers and the product of prime numbers

awsome explanation! hanx dude