Perfect Retro Numbers (1-3) (6-496) Perfect Numbers are by adding their factors (except the number itself) then if the factors (already added by) are the same value of the number itself, means it's a Perfect Numbers. (Example: Factor of 6: 1 , 2 , 3 (Except for the number itself) 1 + 2 + 3 = 6)
C2A also plain sounds
