Question

Upon adding a number and its reverse, the result obtained is divisible by ___.

Answer 1

Let the number be ab, i.e. 10a + b.

The reverse would be ba, i.e. 10b + a

Addition = 10 a + b + 10b + a = 11a + 11b = 11(a + b)

which has a multiple 11, so addition of a number and its reverse is always divisible by 11.