Question

The sum of a two digit number and the number obtained by reversing its digits is always divisible by

• A. 3
• B. 9
• C. 11

Answer 1

The correct option is C 11

Consider the number ab
ab = 10$\times$a + b
Reverse of ab is ba.
ba = 10$\times$b + a
Sum of the number and its reverse is,
ab + ba = 10$\times$a + b + 10$\times$b + a
$\Rightarrow$ 10$\times$(a + b) + (a + b) = 11$\times$ (a + b)
It is always divisible by 11.