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BrainTwister #4: Addition subtraction

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

By New Scientist

24 January 2024

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#4 Addition subtraction

Set by Katie Steckles

It is true that 1 + 2 + 3 = 3 + 2 + 1, and the equation remains true if you remove two of the plus symbols: 1 + 23 = 3 + 21.

Starting from the equation 1 + 2 + 3 + 4 = 4 + 3 + 2 + 1, delete three of the plus symbols so the equation is still true.

Can you find a way to do the same for 1 + 2 + 3 + 4 + 5 = 5 + 4 + 3 + 2 + 1, but this time by removing a different set of three pluses than you did in the previous case?

Solution next week

#3…

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