Multiple choice general knowledge math & puzzles

The digit in the units place of a two-digit number exceeds that in the tens place by one. If the number is equal to four times the sum of its digits, find that number!

  1. 9

  2. 10

  3. 11

  4. 12

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the tens digit be t and units digit be u. Given u = t + 1 and 10t + u = 4(t + u). Substituting: 10t + t + 1 = 4(2t + 1), so 11t + 1 = 8t + 4, giving 3t = 3 and t = 1. Therefore u = 2, and the number is 12. Option D is correct.