The sum of the digits of a two-digit number is 9. If 27 is added to the number, the digits are reversed. What is the number?
A36
B45
C54
D63
Explanation
Let the number be 10x + y. x + y = 9. (10x + y) + 27 = 10y + x => 9y – 9x = 27 => y – x = 3. Solving: x = 3, y = 6. Number is 36.
Exam Relevance
- Topic: Number System
- Subtopic: Digits

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