Why a Number Is Prime
Initializing live version

Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
Move the slider to see that if
is a prime number,
squares cannot be arranged into a rectangular array unless the width or length is 1. That is, it is not possible to represent a prime as the product of two integers
with
.
Contributed by: Enrique Zeleny (March 2011)
Open content licensed under CC BY-NC-SA
Snapshots
Details
Permanent Citation