Question

A $3$-digit number 'cba' is divisible by $9$ if _____ .

• A. $a+2b+c$ is divisible by $9$
• B. $2a+b+c$ is divisible by $9$
• C. $a+b+2c$ is divisible by $9$
• D. $a+b+c$ is divisible by $9$

Answer 1

The correct option is D $a+b+c$ is divisible by $9$

Divisibility Test for $9$ :

$\to$ A number is divisible by $9$ if the sum of the digits is divisible by $9$.

For Example,

$549$ is divisible by 9 since the sum of the digits is $18$ and $18$ is Divisible by $9$.

Here,

Given number is 'cba'

For it to be Divisible by $9$,

(a+b+c) should be divisible by $9$

$\therefore$ Answer is 'D'