def isPrime(n):
	"""
	Checks if a natural number is prime

	:param n: the number (a positive integer) being checked
	:return: boolean
	""" 

	# prime larger than sqrt(n) cannot divide n (Number Theory 101)
	cap = int( n**(.5) )

	if n % 2 == 0: # remove the single even case
		return False

	for i in range(3, cap, 2): # ... to run through possible odd divisors
		if n % i == 0:
			return False
	else:
		return True