What's new

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!

brain icon
 

Brainteaser hint

What’s the difference between two consecutive counting numbers?

brain icon

Brainteaser answer

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

For more brainteasers and puzzles for kids, subscribe to Double Helix magazine!

Subscribe now! button

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

Leave a Reply

By posting a comment you are agreeing to the Double Helix commenting guidelines.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Double Helix Magazine ad

Give the gift of science this holiday season with a discount subscription to Double Helix! Hurry as it’s a strictly limited offer! Subscribe online today.