WBCS.LIVE practice question

Summation of unit place and ten place digits of a number is 9. After interchanging the digits the difference between the earlier and present numbers is 9. What is the number?

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 72
  2. 18
  3. 54
  4. 63

Correct answer and explanation

Correct answer: 54

Explanation: āœ… Correct Answer: C. 54 šŸ“š Explanation: Let the digits be x and y. x + y = 9. The original number is 10x + y and the new is 10y + x. The difference is 9 multiplied by (x - y). Given the difference is 9, x - y must be 1. Solving x + y = 9 and x - y = 1, we get x = 5 and y = 4. Thus, the number is 54.