Question

one of the digits of a two digit number is twice the other digit. the sum of the original numbers amd the number formed by reversing the digits is 99. find the number

Answer 1

let the original number be xy and as one of the digits of this two digit number is twice the other digit. let us assume x = 2y

given that xy + yx = 99

⇒ 10x + y + 10y + x = 99

⇒ 20y + y + 10y + 2y = 99

⇒ 33y = 99

⇒ y =3

⇒ x = 6

so the original number is 63 and the reverse is 36

⇒ 63 + 36 = 99