Which number is divisible by 3? a. 137 b. 60 c. 94 d. 40

One way to find if  a number is divisible by 3  without actually doing the division is to add up the digits of the number until you get 1 digit then if this number is 3,6 or 9 then the number is divisible by 3. 
For example 137:-  1 + 3 + 7 = 11. 1 + 1 = 2  - so not divisible by 3.
The answer here :-  60 is the only one divisible by 3.