Math = Love: The 5-4-3-2-1 Challenge from Will Shortz and NPR

## Monday, October 24, 2016

### The 5-4-3-2-1 Challenge from Will Shortz and NPR

On Sunday morning, Nancy Swank tweeted me a link to a puzzle on NPR's website.  This shouldn't come as a surprise because Nancy is the entire reason why NPR spent an entire day in my classroom in 2014.

I followed the link and started reading the puzzle.  Within about a minute, I knew I HAD to do this puzzle with my students this week.  Here's the link to the puzzle from NPR so you can check it out yourself.

I'm naming this puzzle the "5-4-3-2-1 Challenge."

In the same style as my 2016 Challenge Posters, I made a set of 5-4-3-2-1 Challenge Posters.  After students find a solution and get it checked, they can write the solution on the poster and sign their name next to it.  To keep things organized, I pre-typed the 5 4 3 2 1 part of the solution.  Students will only have to write in the mathematical operators and parentheses.

Since the challenge is to find as many numbers from 1 to 40 as possible, I designed the posters to hold the solutions to 10 numbers each.  These posters are designed to print on 11 x 17 cardstock (affiliate link).  I use this cardstock for so many posters in my classroom!

To help students solve this puzzle, I decided to design a template for students to slide into their dry erase pockets.  This lets them draw and erase and repeat over and over and over as they work through the puzzle.

The cheapest way to get dry erase pockets for your classroom is to search Amazon for "shop ticket holders (affiliate link)."  These let you slide any sheet of paper inside and instantly turn it into an interactive activity!

If you don't have dry erase pockets, I also made some 5-4-3-2-1 strips that could be printed and laminated.  Then, students could write directly on them with their dry erase marker.

By the time I had made all of these resources, I decided I wanted something to help me keep track of all of my solutions.  I had started working on this puzzle briefly while waiting for Sunday School to start, but my answers were just jotted on random paper in random order.  I needed a way to figure out which numbers had solutions and which didn't.

So, I came up with this:

I printed one sheet off for me and one for my husband.  He didn't ask for one, but I know he can't resist a puzzle.  If I was going to be tortured by this puzzle, I was going to bring him along for the ride, too!  So, after lunch on a Saturday afternoon, we sat on our respective couches and tried our hands at this puzzle.

I don't want to spoil the puzzle for anyone because I hate when somebody does that to me.  But, I will confirm that I was NOT able to find solutions for all 40 of the numbers.  Is that what should have happened?  I think it is.  Here's the exact wording from Will Shortz and NPR:

It says, "What number or numbers can you not get?"  I will say that Shaun and I arrived at the exact same solution, so we are pretty confident in it.  But, at the same time, I wouldn't be too surprised if someone showed me that my solution was wrong in some way.

I guess I'll have to wait a week for the solution to be posted...

Want the files to try this out with your own students?  Or, maybe you just want to try the puzzle out for yourself?  Here's the link to download the files.

1. Well, I am almost done. Not sure if you want it posted where I am stuck- certainly not giving any spoilers on here! But it was fun- I wonder how long it will take my students?

2. Thanks Sarah. Was just looking for something new for my "puzzles" bulletin board. I just introduced students the graphing calculators and that the calculators "know" order of operations. So I'm going to have my students do this on the dry erase templates, then show me the solution on their new calculators to drive home the point:)

3. It was fun watching this take off on the #MTBoS! (P.S. I use heavy duty sheet protectors for inexpensive dry erase pockets - they work well!)

4. Will's wrong BTW: ((4*2)+5)*3*1

1. Order must be 5 4 3 2 1

5. By Sunday afternoon I got all but a handful of the integers in the 30s. Will Shortz stated that all are possible except 39. Will you be posting solutions? I tried a "systematic" approach (instead of an unrelated series of trials, which did not pan out. To post a system would be interesting.

6. The files are no longer available to download. Would you be able to email them to me?