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Count by adding

By David, 3 August 2020 Brainteaser

Difficulty: Fun

I’m thinking of three numbers.

They are consecutive counting numbers.

When you add the first two numbers together, you get the third number.

What numbers am I thinking of?

Scroll down or click for a hint, or the answer!

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Brainteaser hint

What’s the difference between two consecutive counting numbers?

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Brainteaser answer

The numbers are 1, 2, 3 as 1 + 2 = 3.

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4 comments

  1. There is a second possible answer.
    The numbers are -1, -2, -3 as -1 + -2 = -3.

      Reply
    1. Nice one!

      I guess this one only works if you think negative numbers are counting numbers. (And I guess whether you think it’s okay to be counting down) but it’s still a great answer!

        Reply
    2. No problems! I love it when people push our puzzles right to the limit. Puzzles can be a bit tricky to write and we sometimes make mistakes, so it’s always nice to get a comment that is adding to the question and not telling us we’ve got it wrong!

        Reply
  2. Thanks. After posting I realised your intent of counting numbers was likely to limit it to positive numbers.

    The fun of many of these brainteasers is in exploring possibilities.

      Reply

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