Let us suppose that these black dots represent a succession of pillar boxes. It will be seen that a postman, starting from the circle, and going along the dotted lines, turns round 18 corners.
Can he take a course which involves fewer turnings?
No. LXX.—TRANSFORMATIONS
Here is an ingenious paper and scissors puzzle:—
Divide a square card into three pieces, so that these can be reunited to form No. 2 or No. 3 of this diagram.