2023 · Q9
The sum of digits of a 2-digit number is 12. When the digits are reversed, the number becomes greater by eighteen. What is the difference between the digits in the number?
Elementary MathematicsNumber System
- A1
- B2
- C3
- D4
Explanation
Write the number as 10x + y with x + y = 12. Reversing the digits increases it by 18: (10y + x) − (10x + y) = 9(y − x) = 18, so y − x = 2. The difference between the digits is 2 (B).