# Large Integers

Here you can play with very large numbers, specifically large integers. Handling these large numbers on a computer is not straightforward. Computers normally keep numbers as binary, typically in a word (32 bits) or double word (64 bits). This only allows for an integer of up to about 4.3 billion or 18.5 quintillion; not very big when you think about it.

If you want larger numbers then you need to go beyond the computer's intrinsic integer size. Suffice it to say when you do that the arithmetic is no longer trivial. Computers have an add and multiply which works fine on small numbers. Not so much on large ones. Big number arithmetic must be done using algorithms implemented by programmers.

Here we have a Factorial Calculator. As you recall, to calculate n factorial (denoted n!) one multiplies n by n-1, etc down to 1.

n! = n x (n-1) x (n-2) x ... x 3 x 2 x 1

Factorials easily generate very large integers.

Just look at how these factorials for small numbers increase:

7! = 5,040

8! = 40,320

9! = 362,880

10! = 3,638,800

As you can see the result gets large very quickly. What do you think 100! is? Try it.