ABSTRACT
Th e maximum number of square outlines that can be produced on the plane from the four identical square frames is 18.
Th e symbol on the top left should be placed in the top left cell of the checkered 4 × 4 paper square. If you fold the square in the four different ways as shown in the diagrams A through D, you will see four diff erent stylized digits-1, 2, 3, and 4-which appear when two cells of the square overlap each other.
