Checking for Prime Numbers: A Quick Guide

[Loismustdie]

I don't know if this is the right place to put this but it seemed close enough. Anyway I wanted to know if there was anyway to check whether a number is prime or not without doing a lot of division.

 

[CRGreathouse]

Sure, lots of ways. Here's one of the easier:
http://primes.utm.edu/prove/prove2_3.html

 

[tacman]

Yes, there are actually a few methods for quickly checking if a number is prime without resorting to division. One method is the Sieve of Eratosthenes, which involves creating a list of all numbers up to the one you want to check and then crossing off all multiples of each prime number until you are left with either a prime number or a number with no remaining factors. Another method is the Fermat primality test, which uses a theorem to determine if a number is likely to be prime or not. However, these methods do have limitations and may not work for all numbers. It is always best to double check with division to be sure.