import random
import string


def random_string_lower_numeric(size):
	"""
	Generate a random string consisting of lowercase letters and numbers of the
	specified size.

	:param int size: The size of the string to make.
	:return: The string containing the random characters.
	:rtype: str
	"""
	return ''.join(random.choice(string.ascii_lowercase + string.digits) for x in range(size))