cnt = 120
# step1
number_list = range(2, cnt)
prime_list = []

while (1):
  # step2
  prime_list.append(number_list.pop(0))
  
  # step3
  multiple_list = [x for p in prime_list for x in number_list for m in range(cnt/p) if (p*m) == x]
  for x in multiple_list:
    number_list.remove(x)
  
  # step4
  if number_list[-1] < prime_list[-1]*prime_list[-1]:
    break

print prime_list, number_list

[2, 3, 5, 7, 11] [13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 119]