These two tricks are fun to try just once.
Trick #1
Ask a friend to pick a two-digit number between 1 and 50.
Both digits must be odd, and they must be different.
For instance, you cannot choose 11.
After your friend has chosen her number, ask if it is 37.
Why does this work (or not work)?
Most people choose the number 37. The second most commonly picked number is 35.
There are only eight numbers that satisfy the conditions.
Trick #2
Ask a friend to pick a two-digit number between 50 and 100.
Both digits must be even, and they must be different.
After your friend has chosen her number, ask if it is 68.
Why does this work (or not work)?
Most people choose the number 68.
There are only eight numbers that satisfy the conditions:
60, 62, 64, 68, 80, 82, 84, and 86.
Many thanks to Lloyd Mobley Jr. for catching my error when I asserted that there were only six possibilities.