Question

If 20𝑎3 is a 4-digit number and a multiple of 3, then sum of the possible values of 𝑎 is:

• A. 7
• B. 4
• C. 12
• D. 5

Answer 1

The correct option is C 12

If 20$a$3 is a multiple of 3, then it is exactly divisible by 3.
For a number to be divisible by 3, the sum of its digits should be divisible by 3.
= 2 + 0 + $a$ + 3
= 23 + $a$
For 23 + $a$ to be divisible by 3, possible values of $a$ can be 1, 4, 7.
Sum of the possible values of $a$ = 1 + 4 + 7 = 12