# Python | Program to find factorial of a number

This is an example of how to find the factorial of a number in python.

The factorial of a number is a product of all the positive integers less than or equal to that number.

For example, the factorial of 5 is 5x4x3x2x1 = 120

*Factorial is not defined for negative integers, and the factorial of zero is one, 0! = 1.*

Check here for factorial recursive way

```
n = int(input('Enter no.:'))
fact = 1
for i in range(1,n+1):
fact *= i
print(fact)
```

Output for the above code

_{>>> ====================== RESTART: E:\py\factorial.py ====================== Enter no.:5 120}

let's modify the code to handle number less than or equal to zero

```
n = int(input('Enter no.:'))
fact = 1
if n < 0:
print(f"Sorry, factorial does not exist for {n}, negative number")
elif n == 0:
print("The factorial of 0 is 1")
else:
for i in range(1,n+1):
fact *= i
print(fact)
```

Output for the above code

_{>>> ====================== RESTART: E:\py\factorial.py ====================== Enter no.:5 120 >>> ====================== RESTART: E:\py\factorial.py ====================== Enter no.:0 The factorial of 0 is 1 >>> ====================== RESTART: E:\py\factorial.py ====================== Enter no.:-5 Sorry, factorial does not exist for -5, negative number}