Question

A number consists of two digits of which ones digit exceed the tens digit by 1. The number itself is equal to four times the sum of its digits. Find the number.

Answer 1

Let the 2 digit number be ab. [b-one's place, a-ten's place]
b - a = 1
Possibilities (12), (23), (34), (45), (56), (67), (78), (89)

Also given: Number = 4 times sum of its digits.
So the number has to be multiple of '4'
Possibilities (12), (56)
12 = 4*(1+2)
Hence the number is 12.
Hope it helps.