A two-digit number is 36 more than the number obtained by interchanging its digits. What is the difference between the two digits of the number?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4
With tens digit \(a\) and units digit \(b\), the number is \(10a+b\) and the reversed number is \(10b+a\). Their difference is always \(9(a-b)\).
\((10a+b)-(10b+a)=9a-9b=9(a-b)\)
\(9(a-b)=36\)
\(a-b=36\div9=4\)
Example: \(51-15=36\)
The digits differ by 4.
Why the other options are incorrect
Option (1) 9 — Incorrect. If the digits differed by 9, the two numbers would differ by \(9\times9=81\), not 36.
Option (2) 6 — Incorrect. If the digits differed by 6, the two numbers would differ by \(9\times6=54\), not 36.
Option (3) 3 — Incorrect. If the digits differed by 3, the two numbers would differ by \(9\times3=27\), not 36.