# Factorial program in c using while loop

In this post, you will learn how to find the **factorial** of a number in the **C** programming language using a while loop.

The factorial is normally used in different areas of mathematics, including algebra, mathematical analysis, and combinations and permutations. The factorial of a number **n** is denoted by **n!**. This is the product of all positive numbers less than or equal to **n**. It is calculated as-

**n! = n X (n-1) X (n-3) X ……… X 3 X 2 X 1**

### An example of factorial

Suppose we want to get a factorial of 7, then the factorial will be-

```
7! = 7 X 6 X 5 X 4 X 3 X 2 X 1
5040
```

## Factorial program in C using while loop

In the given **C** program, we ask the user to enter a number and store it in a variable **num**. The while loop continues till the value of **num** greater than or equal to the value of **i**. Then within the loop, the value of '**i**' is multiplied with the value of '**fact**'. Finally, we get the factorial value of the given number.

```
#include <stdio.h>
int main()
{
int i,fact=1,num;
fact=i=1;
printf("Enter a number: ");
scanf("%d",&num);
while(i<=num)
{
fact*=i;
i++;
}
printf("The Factorial of %d : %d",num,fact);
return 0;
}
```

**Output of the above code:**

```
Enter a number: 7
The Factorial of 7 : 5040
Enter a number: 11
The Factorial of 11 : 39916800
```

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