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BrainTwister #73: Square dance

Can you solve this week’s logic puzzle? Plus our quick quiz and the answer to last week’s problem

By Sam Hartburn

14 May 2025

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Shutterstock/ktsdesign

#73 Square dance

Set by Sam Hartburn

If you arrange five square tiles, each with side length 1, in a bigger square as shown, what proportion of the area of the square do the tiles use (to three decimal places)?

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

One of the tiles is rotated by 45 degrees and all five are arranged inside a smaller square as shown. What is this square’s area? What proportion of that area do the tiles use?

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Ten tiles in a 4-by-4 square use up 10/16 = 0.625 of the area. But with four of them rotated by 45 degrees, they fit in…

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