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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

Âé¶¹´«Ã½. 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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