Let the digit in the tens place of the number be x.
The digit in the units place of the number = 2x
∴ The number = 10(x) + 2x = 12x
Sum of the digits = x + 2x = 3x
Given that the number exceeds the sum of its digit by 18.
⇒ 12x = 3x + 18
⇒ 9x = 18
⇒ x = 2
Therefore, the digit in the tens place is 2 and the digit in the units place is (2 x 2) i.e. 4.
So, the number is 24.