Question

3a21 is divisible by 3 and 9 , what should be the value of a

• A. 3
• B. 5
• C. 6
• D. 9

Answer 1

The correct option is A

3

If a number is divisible by 3 and 9 , then the sum of the digits should be divisible by 3 and 9

Given that 3a21 is divisible by 3 and 9

The sum of the digits = 3 + a + 2 + 1 = 6 + a = 9 , 18 , 27.....( Taking the numbers which are divisible by 3 and 9)

If 6 + a = 9 ; a = 3

If 6 + a = 18 ; a = 12

If 6 + a = 27 ; a = 21

Since 12 and 21 are two digit numbers , Hence only possible value of a = 3