Question: 2 digit number is reversed?
Answer: When a 2 digit number is reversed and added to the original number, the result is divisible by 13. This resultant number has to be divisible by 13. We know that 11 is not divisible by 13, this basically means that (a+b) must then be divisible by 13, because 11(a+b) as a whole must be divisible by 13.