Multiple choice

A two-digit number is such that the product of the digits is 8. When 18 is added to the number, then the digits are reversed. What is the number?

  1. 18

  2. 24

  3. 42

  4. 81

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the ten's and unit digit be x and 8/x, respectively. Then, (10x + 8/x) + 18 = 10 x (8/x) + x 10x2 + 8 + 18x = 80 + x2 9x2 + 18x - 72 = 0 x2 + 2x - 8 = 0 (x + 4)(x - 2) = 0 x = 2. So, unit's digit = 4 and ten's digit = 2 Then, the required number is 24. Therefore, the correct answer is 24.

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