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BrainTwister #83: Doubled squares

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

By Colin Beveridge

23 July 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.

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#83 Doubled squares

Set by Colin Beveridge

Can you find a three-digit square number that is 1 more than double a square number?

Can you find a four-digit square that is 1 more than double a square?

What is the smallest square that is 1 more than double a square that has a different number of digits?

Solution next week

#82 Flipping coins

Solution

Action #3 flips HH to TT in one move.

Yes, doing a pair of actions gives the same result whichever one is done first.

There are five ways to get from HH to TT without returning to a previous position: #1 then #2; #2 then #1; #1 then #3 then #1; #2 then #3 then #2; or #3.

Quick quiz #312

set by Corryn Wetzel

1 How many chambers does the human heart have?

2 Who holds the record for the longest single stay in space, at 437 days?

3 What tree produces the largest seeds in the world?

4 In what year did Rosalind Franklin capture “Photograph 51”, pivotal to discovering DNA’s structure?

5 What bacterium causes Lyme disease?


Quick quiz #312

Answers

1 Four

2 Valeri Polyakov

3 The coco de mer palm (Lodoicea maldivica)

4 1952

5 Borrelia burgdorferi

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