# C++ Program to Find Factorial of a Numbers

In this example, we will learn to Find the Factorial of a number using For Loop and While Loop.

To understand this example, you should have the knowledge of the following C++ programming topics:

## Factorial of a Numbers

For any positive number `n`, it's factorial is given by:

factorial = 1*2*3...*n

Factorial of negative number cannot be found and factorial of 0 is 1.

In this program below, user is asked to enter a positive integer. Then the factorial of that number is computed and displayed in the screen.

## Example 1: Program to Find Factorial of a given number using for loop.

```
// C++ Program to Find the Factorial of a number using For loop.
#include <iostream>
using namespace std;
int main()
{
unsigned int n;
unsigned long long factorial = 1;
cout << "Enter a positive integer: ";
cin >> n;
for(int i = 1; i <=n; ++i)
{
factorial *= i;
}
cout << "Factorial of " << n << " = " << factorial;
return 0;
}
```

**Output**

Enter a positive integer: 5 Factorial of 5 =120

##### Working of above Program:

Here variable `factorial` is of type `unsigned long long`

.

It is because factorial of a number is always positive, that's why
`unsigned`

qualifier is added to it.

Since the factorial a number can be large, it is defined as `long long`

.

## Example 2: Program to Find Factorial of a given number using while loop

```
// C++ Program to Find the Factorial of a number using While loop
#include <iostream>
using namespace std;
int main() {
int n, f = 1, i = 1;
cout << "Enter a positive integer: ";
cin >> n;
// Loop to calculate the factorial of a number
while (i <= n) {
f=f*i;
++i;
}
cout << "Factorial of " << n << " = " << f;
return 0;
}
```

**Output**

Enter a positive integer: 5 Factorial of 5 =120

Here variable `f` is of type `int`

.

It is because factorial of a number is always positive, that's why
`unsigned`

qualifier is added to it.

##### Working of above Program:

- First the computer reads the number to find the factorial of the number from the user.
- Then using while loop the value of ‘i’ is multiplied with the value of ‘f’.
- The loop continues till the value of ‘i’ is less than or equal to ‘n’. Finally the factorial value of the given number is printed.

## Next Example

We hope that this Example helped you develop better understanding of the concept of "Find Factorial" in C++.

**Keep Learning : )**

In the next Example, we will learn about C++
`Program to Generate Multiplication Table`

.