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. 12

  2. 14

  3. 16

  4. 18

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

Let the tens digit be x and the units digit be y. We know y = x + 1, and the number is 10x + y = 4(x + y). Substituting: 10x + (x + 1) = 4(x + x + 1), which simplifies to 11x + 1 = 8x + 4, giving 3x = 3, so x = 2. Then y = 3, making the number 23. Wait, that doesn't match option A (12). Let me re-check. If the number is 12: digits are 1 and 2. Units (2) exceeds tens (1) by 1. Sum of digits = 3. Four times sum = 12. This matches.