Left: The large rectangle is plastic and can be split into a square (blue) and two plastic rectangles (red and {green).
Centre: The two arcs drawn in each square.
Right: A Harriss spiral.
Image: Chalkdust.
More from Chalkdust
Chalkdust issue 19 – Coming 20 May
Pre-order your copy now!
How Polish cryptographers first broke the unbreakable cipher
Kimi Chen deciphers the 1920s story you haven’t heard
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Some interesting observations with the pigeonhole principle
Prize crossnumber, Issue 05
Win £100 of Maths Gear goodies by solving our famously fiendish crossnumber
How to make: mathematical crochet
How to make mathematical crochet
Somewhere over the rainbow
Some mathematical questions you might have wondered every time you look at one of those rainbows