(a) We know that a number is divisible by 3 if the sum of all digits is divisible by 3.
Therefore, Smallest digit : 2 --> 26724 = 2 + 6 + 7 + 2 + 4 = 21
Largest digit : 8 --> 86724 = 8 + 6 + 7 + 2 + 4 = 27
(b) We know that a number is divisible by 3 if the sum of all digits is divisible by 3.
Therefore, Smallest digit : 0 --> 476502 = 4 + 7 + 6 + 5 + 0 + 2 = 24
Largest digit : 9 --> 476592 = 4 + 7 + 6 + 5 + 0 + 2 = 33