Question

The first two digits of a 3 digit number are 3 and 7. What are the possible values of the unit's digit if the number is divisible by 3?

• A. 2
• B. 5
• C. 8
• D. 9

Answer 1

Answer: (A), (B), (C)

The correct options are
A

2

B

5

C

8

For a number to be divisible by 3, the sum of its digits should be equal to a multiple of 3.

The sum of the 2 given digits is 3 + 7 = 10.

Hence, if 2 is in the units digit, the sum of the digits will be 3 +7 +2 = 12, which is a multiple of 3.
$\therefore$372 is divisible by 3.

if 5 is in the units digit, the sum of the digits will be 3 +7 +5= 15 which is a multiple of 3.
$\therefore$375 is divisible by 3.

if 8 is in the units digit, the sum of the digits will be 3 +7 +8 = 18, which is a multiple of 3.
​​​​​​​$\therefore$378 is divisible by 3.

if 9 is in the units digit, the sum of the digits will be 3 +7 +9 = 19, which is not a multiple of 3.
​​​​​​​$\therefore$379 is not divisible by 3.