When we multiply a certain two-digit number

When we multiply a certain two-digit number by the sum of its digits, 405 is achieved. If you multiply the number written in reverse order of the same digits, we get 486. Find the number?

  1. 81
  2. 45
  3. 36
  4. 54

Solution

Two-digit number is a factor of 405. Going by the options, only 81 and 45 are factors of 405.

Multiplying the number by its sum of digits, the result should be 405.

81 x (8+1) = 81 x 9 = 729

45 x (4+5) = 45 x 9 = 405

The correct option is B.