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Post-It Note Puzzle

Today I want to share one of my favorite puzzles that I used with my students last year. It involves one of my favorite things in the world, Post It Notes!

post it note puzzle

I learned about this puzzle from Chris Smith‘s amazing maths newsletter. If you’re not signed up to receive his newsletters, you need to do so ASAP. Each one is full of fun puzzles, teaching ideas, and so much more.

Here are the instructions for signing up:

Chris Smith Maths Newsletter Tweet

The featured puzzle from Volume 373 definitely caught my eye.

Post-It Note Puzzle

I recreated it with actual post-it notes on my dry erase board.

Post It Note Puzzle on Dry Erase Board

My students were instantly drawn in. At first, they assumed the puzzle would be super easy. After struggling for a few minutes with no success, some students started doubting the puzzle’s solvability. I loved that when a student thought he/she had arrived at a solution that it could be verified by actually moving the post-it notes.

Some classes did manage to arrive at a solution. Others gave up. I used this puzzle as a random time filler last year. This year, I’m considering incorporating it into my first week of school activities.

Puzzle Solutions

I intentionally do not make answers to the printable math puzzles I share on my blog available online because I strive to provide learning experiences for my students that are non-google-able. I would like other teachers to be able to use these puzzles in their classrooms as well without the solutions being easily found on the Internet.

However, I do recognize that us teachers are busy people and sometimes need to quickly reference an answer key to see if a student has solved a puzzle correctly or to see if they have interpreted the instructions properly.

If you are a teacher who is using these puzzles in your classroom, please send me an email at with information about what you teach and where you teach. I will be happy to forward an answer key to you.

More Number Puzzles


Wednesday 19th of May 2021

can you share the solution. I was looking for something for this morning and don't have time to solve.

Natalie Moon @themathgirl

Saturday 17th of August 2019

Once I read your note about exponents or flipping over I got it immediately. I wonder what hint I could give to students.


Friday 11th of August 2017

I can figure it out if I can remove one post it note. But all the numbers together equal 39 so I don't see how you can get each line to equal the same number. 39 isn't divisible by 2! Help!!

Sarah Carter (@mathequalslove)

Wednesday 6th of September 2017

You have to get tricky. Use exponents. Or flip a post-it note over, etc.


Tuesday 8th of August 2017

I love this kind of stuff with my middle schoolers! Thank you for the newsletter sign up info!

Sarah Carter (@mathequalslove)

Sunday 10th of September 2017

You're Welcome!

Brian Q.

Monday 7th of August 2017

Sarah, do you have a link to a hint or solution? This puzzle looks great for my class!

Sarah Carter (@mathequalslove)

Sunday 10th of September 2017

Possible Solutions:

Comments are closed.