Reputation: 12399

calculating factorial in Python

When calculating

math.factorial(100)

I get:

93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000L

Why is there an L at the end of the number?

Upvotes: 1

Answers (5)

Nishant Chaudhary

Reputation: 1

Python factorial using for loop

def fact(n):
  if n<=1:
    print("Enter a positive no.")
  else:
    for i in range(n,1,-1):
      n = n*(i-1)
    return n
print(fact(int(input("Enter a number : "))))

Upvotes: 0

Eric He

Reputation: 11

you could use the factorial calculator code...

def factorial (number):
    product=1;
    for i in range(number):
        product=product*(i+1)
    return product

I do not have Python, so I did not test out the code. I guarantee that this function will work.

Upvotes: 0

Hamish Grubijan

Reputation: 10820

I believe that you are working with a BigInt, which is known as long in Python - it expands and occupies a variable amount of RAM as needed. The name long can be confusing, as that means a specific number of bytes in a handful of popular languages of today. The following can help you get at the number of bytes it takes to store the object.

Python 2.6.2 (r262:71600, Aug 14 2009, 22:02:40) 
[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 
>>> import sys
>>> a = 1
>>> sys.getsizeof(a)
12
>>> import math
>>> sys.getsizeof(math.factorial(100))
84
>>> sys.getsizeof(math.factorial(200))
182
>>>

Upvotes: 1