Ref: Prof. Ian Stewart’s Cabinet of Mathematical Curiosities
Farmer Hogswill has run into another mathematico-agricultural problem. He had carefully assembled 13 identical fence panels to create 6 identical pens for his rare-breed Alexander-horned pigs. But, during the night some anti social person stole one of his panels. So, now he needs to use 12 fence panels to create 6 identical pens. How can he achieve this? All 12 panels must be used.
More later.
Nalin Pithwa.
Mathematics Hothouse 
One Comment
He arranges them in a hexagon-like structure with sides and diagonals as panels.