Mystery Number
What is the mystery number? If I subtract 1 / 2 of it, then multiply by 3, and then add 2, the end result is 26.
(Source: from Mathematics Teaching in the Middle School, JanMar1995)

Extensions 
Write your own mystery number problem to have a classmate or friend solve. Make sure that your number goes through three transformations (addition, subtraction, multiplication or division). 
Submit your idea for an investigation to InterMath.
