There are lots of iterations of numbers games like this, but this one is especially nice because it’s open-ended and repeatable, and can be extended to your grade level. Marilyn Burns has published several variations of this game like this one, or many more from her book, About Teaching Mathematics among others. I’m sure that I’m not alone when I say that Marilyn is my hero. These games are full of thinking and practical number sense, and require almost no prep. This one is a perfect back-pocket activity if you have a few idle minutes (though I can’t actually remember that ever happening – we always seem to have too much to do!), or a nice way to regularly open or close class.
My kids love this game, and ask for it if we haven’t played it for a while. I heard about it first from Tom at the Dana Hall Math Workshop. I mentioned how much I loved this conference in an earlier post.
Here’s how the game works
- Choose 4 numbers between 1 and 10
- Choose 1 multiple of 10 between 20 and 100
- And choose one 3-digit number between 200 and 1000 (Your Target Number)
- Use the first five numbers and any operations to get as close as you can to the 3-digit number.
Example: 4,8,3,2,70 Target 497
First Try: 70 x 8 = 560-4x3x2 = 560-24 = 536
A Better Attempt: (4+3)x70 = 490+8-2 = 496
I’ve opened this up to include exponents or roots, with pretty good success. Do let me know if you use this, or have any variations up your sleeve.