Question

The sum of a 2-digit number ab and the number obtained by reversing its digits is 66. Find the value of 4(a + b).

Answer 1

Here, ab is a 2-digit number.
Number obtained by reversing its digits is ba.

Expanded form of the 2-digit number ab = 10a + b

Expanded form of the 2-digit number ba = 10b + a

Adding both, we get
(10a + b) + (10b + a)
= 11a + 11b
= 11(a + b)

Given 11(a+b) = 66
i.e, a + b = 6

Therefore, 4(a + b) = 4(6) = 24