isPrime

basic idea

def is_prime(num):
    '''
    Naive method of checking for primes. 
    '''
    for n in range(2,num):
        if num % n == 0:
            print 'not prime'
            break
    else: # If never mod zero, then prime
        print 'prime'

improved version:

We can actually improve this by only checking to the square root of the target number, also we can disregard all even numbers after checking for 2.

import math

def is_prime(num):
    '''
    Better method of checking for primes. 
    '''
    if num % 2 == 0 and num > 2: 
        return False
    for i in range(3, int(math.sqrt(num)) + 1, 2):
        if num % i == 0:
            return False
    return True