1. A farmer had several pens out by the barn. He had used 17 lenghts of fence to make the pens, but now he needs to use six of those fence lengths for another project. He wants to remove six fence lenghts but still have two square pens remaing. Which lenghts should he remove?

Answer 1

The equivalent idea is to make two square pens out of 17-6=11 match-sticks. They are attached together.