def test_low(self):
        cases = [(0, "영"), (1, "일"), (2, "이"), (3, "삼"), (4, "사"), (5, "오"),
                 (6, "육"), (7, "칠"), (8, "팔"), (9, "구"), (10, "십"),
                 (11, "십일"), (12, "십이"), (13, "십삼"), (14, "십사"),
                 (15, "십오"), (16, "십육"), (17, "십칠"),
                 (18, "십팔"), (19, "십구"), (20, "이십"), (25, "이십오"),
                 (31, "삼십일"), (42, "사십이"), (54, "오십사"), (63, "육십삼"),
                 (76, "칠십육"), (89, "팔십구"), (98, "구십팔")]
        for num, out in cases:
            self.assertEqual(n2k(num), out)