Which of the following numbers is divisible by 3?

(a) 1212

(b) 625

(a) Given number = 1212

Sum of the digits = 1 + 2 + 1 + 2 = 6, which is divisible by 3.

Hence, 1212 is also divisible by 3.

(b) Given number = 625

Sum of the digits = 6 + 2 + 5 = 13, which is not divisible by 3.

Hence, 625 is not divisible by 3.