Question

How many of the following numbers are divisible by $3$ but not by $9$?
$2133,2343,3474,4131,5286,5340,6336,7347,8115,9276$

• A. $5$
• B. $6$
• C. $7$
• D. None of these

Answer 1

The correct option is B $6$

Marking (/) those which are divisible by $3$ by not by $9$ and the others by (X), by taking the sum of digits, we get
$2133\to 9$ (X)
$2343\to 9$ (/)
$3474\to 9$ (X)
$4131\to 9$ (/)
$5286\to 9$ (/)
$5340\to 9$ (X)
$6336\to 9$ (X)
$7347\to 9$ (/)
$8115\to 9$ (/)
$9276\to 9$ (/)
Required number of numbers $=6$