Multiple choice general knowledge math & puzzles

The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 36. What is the difference between the two digits of that number?

  1. 3

  2. 4

  3. 9

  4. None of these
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B Correct answer
Explanation

Let the two-digit number be 10a + b, where a and b are the digits. When interchanged, it becomes 10b + a. The difference is (10a+b) - (10b+a) = 9(a-b) = 36, so a-b = 4. The digit difference is 4.

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