You may also like

problem icon


What would be the smallest number of moves needed to move a Knight from a chess set from one corner to the opposite corner of a 99 by 99 square board?

problem icon

2001 Spatial Oddity

With one cut a piece of card 16 cm by 9 cm can be made into two pieces which can be rearranged to form a square 12 cm by 12 cm. Explain how this can be done.

problem icon


A cylindrical helix is just a spiral on a cylinder, like an ordinary spring or the thread on a bolt. If I turn a left-handed helix over (top to bottom) does it become a right handed helix?

Matching Frieze Patterns

All frieze patterns contain translations of the motif along the strip.

Look for reflections in the axis along the strip and perpendicular to the strip.

Take care to distinguish glide reflections such as p b from rotations such as p d.