# A Mathematician Wrote a 2-Digit Number on a Sheet

A mathematician wrote a 2-digit number on a sheet of paper is a math’s riddle. Here is the correct answer with proper explanation to this math’s riddle. In this riddle you need to guess the correct 2-digit number with the difference of 75.

Riddle: A mathematician wrote a 2-digit number on a sheet of paper. When he turned the sheet upside down, the number decreased by 75. What was the number?

## A Mathematician Wrote a 2-Digit Number on a Sheet Riddle Answer

Answer: The answer to “A mathematician wrote a 2-digit number on a sheet of the paper” is “91.” The correct number is 91 because if you rotate the number upside down it becomes 16 and the difference between these 2 numbers is 75.

## Explanation

There are only few numbers which can be turn upside down and still they will be a valid number like 1, 6, 8 and 9. The combination of this numbers can be the answer so the correct number is 91.

If you rotate the number 91 it becomes 16 and the initial number is decreased by 75.

91 ˗ 16 = 75