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.