Hi all, I'm reviewing some problems that involve finding the prime factors of composite numbers (e.g. prime factors of 44 are 2, 2, 11) and I had two questions about prime numbers and factors of composite numbers: 1) Is there some sort of quick test to tell if a number is prime? Or, does one have to run through every possible divisor in order to see? For example, in one of my problems I came up with 269. I can't tell just by looking at it if this is prime or not. Do I t/f have to start dividing by 3, then try 9, and so on until I can truly say if it's prime or not? Surely some smart person a couple thousand years figured out a faster way... 2) Related to question 1, is there a shortcut to finding the factors of any number - or does it all start and end with basic trial and error of various divisors? Thanks in advance!