I like to introduce this one around Halloween. It's just enough time in the year to really frustrate the students (and the staff!). It is usually an unsuspecting student who is able to solve this one. And boy, are they proud! I like this because it is equally frustrating to all students-and boy is it fun to stump those students who are not used to being stumped! I found this one on
Mitch Adler's page. He has a ton of balanced math problems for all different holidays. So, if you miss Halloween, don't worry. He has Thanksgiving, Christmas, Valentine's, President's Day...