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What a prime number is

We have to be careful by what we mean by a "number". This project is concerned only with positive whole numbers that are prime. Hence a prime number, or just a "prime", is a positive whole number that is greater than 1 and which when it divides a product of two numbers divides at least one of those two numbers. Consequently, a prime number is only divisible by itself and 1; It has no proper factors. 

Although 1 is a positive whole number only divisible by itself and 1, it is treated separately because any number can be forever repeatedly divided by 1.

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