Find factorial of a number in python : Python tutorial 25

What is factorial :

Factorial of a number is the multiplication of all the numbers from 1 to that number e.g. factorial of 3 is 1 * 2 * 3 i.e. 6 . To find factorial, we can either use loops or recursive approach. Following examples will explain you properly how to find factorial of a number in python :

Using for loop :

Using for loop we can iterate from 1 to that specific number we want to find out factorial . On each iteration , we will multiply the final result with current iteration count . final result will be 1 at first. So, after the loop will exit, we will get the factorial of that number .

```def factorialUsingForLoop(n):
fact = 1
for i in range(1,n+1):
print (i)
fact=fact*i

print('Factorial of the number %d is %d'%(n,fact))

if __name__== "__main__":
factorialUsingForLoop(4)
```

Find factorial using while loop :

We can similarly find out the factorial of a number using a while loop. On each time , we will decrease the value of the number by 1 and multiply it with the final result.

```def factorialUsingWhileLoop(n):
fact = 1
while(n>1):
fact = fact*n
n = n - 1

print('Factorial is %d'%(fact))

if __name__== "__main__":
factorialUsingWhileLoop(4)
```

Factorial using Recursion :

Recursion means the same function will be called recursively. To find factorial of a number, we can also use recursive approach like below :

```def factorialUsingRecursion(n):
if (n == 1):
return 1
else :
return n* factorialUsingRecursion(n-1)

if __name__== "__main__":
print "factorial is ",factorialUsingRecursion(4)
```