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?
REVEAL THE ANSWER
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