Number -> Sum of digits -> new sum of digits
363 -> 3 + 6 + 3 = 12 -> 1 + 2 = 3
489 -> 4 + 8 + 9 = 21 -> 2 + 1 = 3
579 -> 5 + 7 + 9 = 21 -> 2 + 1 = 3
471 -> 4 + 7 + 1 = 12 -> 1 + 2 = 3