Broken Calculator Challenge – Target 25 Teachers page

Go to:

http://seeingmath.concord.org/broken_calculator/

and "break" the 1, 8, 5, 2, 0, 3 and - (minus) keys.

List all the different ways you can make 25 on this calculator with keys that are NOT broken. The first one is done for you.

1
7 * 3 + 4 = 25
2

3

4

5

6

7

8


How many of these ways will work on the broken calculator? (The first one is done for you.)

(Only keys that work are: 7, divide, 4, 6, mulitply, open and close parenthesis, add, equal, and cancel.)

Create more challenges for the students to do!

Learn More

Try some more Broken Calculator challenges at
http://www.fi.uu.nl/toepassingen/00014/toepassing_rekenweb.xml?style=rekenweb&language=en&use=game

and

http://www.mathcats.com/microworlds/broken_calculator.html

More Ideas on Using the Broken calculator

Tuesday's lesson - what you can do with a Broken Calculator?
http://www.concord.org/publications/newsletter/2005-fall/tuesday.html

On-math article: Learning Number Sense from a Broken Calculator
Judah Schwartz, George & Judith Collison
https://my.nctm.org/eresources/view_article.asp?article_id=7457&page=1