For amusement he began to fold the trimmed-off strips of paper in various ways ... The triangles on one side are numbered 1, 2 and 3; the triangles on the other, 4, 5 and 6.

Step 1: Fold an 8.5 x 11–inch sheet of paper in half lengthwise, then lay it flat on one side. Step 2: Fold the top two ...