 # C Program to find Factorial of a number

For a better understanding, we always recommend you to learn the basic topics of C programming listed below:

In this C program, we have to find out the Factorial of a given number. So first, we have to check what is Factorial.

## What is the factorial of a number?

The factorial of a number means the product of all the natural numbers up to the given number. An exclamation mark indicates the factorial of a number '!'. Let us consider an example: the factorial of 5 is 5! = 5 * 4 * 3 * 2 * 1. Which is equal to 120.

The logic we applied in this c program is to declare the variable 'i,' num, fac. Then read the number from the user and save it into the variable num. By using a for loop with the condition "i <= n" , calculate fact = fact * i. Finally, display the factorial of the number as 'fact'. the syntax of the if-else statement is

## What is the syntax of the if-else statement?

``````
if (testExpression) {

// codes inside the body of if

} else {

// codes inside the body of else

}
```
```

If the test expression is True, then we execute the code inside the `if` condition, and `else` parts are skipped. But if the test expression is False, we run the else part and ignore the if condition.

### ALGORITHM

STEP 1: Include the header files to use the built-in function in the C program.

STEP 2: Declare the integer variable i, fact, num, and set fact=1.

STEP 3: Read the number from the user and save it into the variable num.

STEP 4: Check if the number is less than or equal to zero `if` valid, then set 'fact=1' and do step 6. `Else` do step 5.

STEP 5: By using the `for loop` with the condition i<=num, calculate fact=fact*i.

STEP 6: Display Factorial of the number num as fact.

## C Source Code

```                                          ```#include <stdio.h>

void main() {
int i, fact = 1, num;
printf("Enter the number\n");
scanf("%d", & num);
if (num <= 0)
fact = 1;
else {
for (i = 1; i <= num; i++) /* multiplying each number below the given number to get the factorial */ {
fact = fact * i;
}
} /* End of else */
printf("Factorial of %d =%d\n", num, fact);
} /* End of main() */```
```

## OUTPUT

```Enter the number
5

Factorial of 5 =  120
```
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