If the number obtained on interchanging the digits of a two-digit number is 18 more than the original number and the sum of the digits is 8, then what is the original number ?
Correct answer: B. 35
- A. 26
- B. 35
- C. 53
- D. Cannot be determined
Explanation
Let the original two-digit number be 10a + b. Interchanging the digits changes it by 9(b - a), so 9(b - a) = 18 and b - a = 2; together with a + b = 8, this gives a = 3 and b = 5. The original number is therefore 35. The likely mistake is 53, which reverses the digits after correctly finding them.
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