GIVEN: The sum of a 2-digit number and the number obtained by reversing its digits is divisible by 12. CONCEPT: Any number of the form ‘ab’ can be written as (10a + b). CALCULATION: Suppose the number is of the form: xy It can be written as: (10x + y) After reversing the number, it will be yx It can be written as: (10y + x) Now, according to the question: [(10x + y) + (10y + x)] is divisible by 12. ⇒ 11(x + y) is divisible by 12. That means (x + y) is divisible by 12. Hence, We need to find all such numbers in form of ‘xy’ where (x + y) is divisible by 12. All possible numbers are: 39, 48, 57, 66, 75, 84 and 93 Now, Sum of all such numbers = [39 + 48 + 57 + 66 + 75 + 84 + 93] = 462