Question

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

• A. 10
• B. 5
• C. 11

Answer 1

The correct option is C 11

Let the 2-digit number be ab

The number ab written in expanded form is 10a + b

If we interchange the digits of ab, the new number is ba.

The number ba written in expanded form is 10b + a

Sum of the number and its reverse is,

Thus, 10a + b + 10b + a = 11a + 11b = 11 (a + b)

So, it is always divisible by 11.