Question

how do you test for primality in java. and if the input is not prime how do you output the product

Answer 1

Use the modulus (%) operator. If 0 the number is even, if not it is odd. Discard number if even (and not 0, depending on how you look at it), then for all odd numbers write a recursive method that breaks down the number into its factors

Answer 2

http://bit.ly/14hhKHQ

Answer 3

For primality there are many different sieves that allow one to find prime numbers up to a given number; you can just use trial division and see if any of these divide your given number.

Answer 4

http://en.wikipedia.org/wiki/Primality_test#Naive_methods