The definition of a factorial is:
n! = n × (n − 1) × … × 2 × 1
or
n! = n × (n − 1)!
We can also use the following definition to calculate the factorial.
0! = 1
1! = 1
2! = 2 * 1 = 2
3! = 3 * 2 * 1 = 6
4! = 4 * 3 * 2 * 1 = 24
Let’s implement this in Python.
def factorial(x):
if x == 0:
return 1
else:
return x * factorial(x-1)
def factorial(n):
result = n
for i in range (1, n):
result *= i
return result
print(factorial(4))
def factorial(a):
if a == 0:
return 1
return a * factorial(a – 1)
print(factorial(5))
from functools import reduce
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
print(factorial(5))
def factorial(num):
if num==1:
return 1
else:
return num * factorial(num-1)
def factorial_norecursion(num):
fact = 1
for i in range(2,num+1):
fact *= i
return fact
print(factorial_norecursion(4))
import math
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
n=int(input(“Input a number to compute the factiorial : “))
print(factorial(n))