There are certain Maths activities that seem to engage students without fail. Broken calculator activities is one of these.
The flash interactive at subtangent has six levels and a time limit on each.
Try this broken calculator which allows you to set which keys are broken.
Transom.org also have some good interactives such as this one.
I first encountered a broken calculator question in the 1980’s. At first sight I did not think it possible. My colleague Keith soon set me straight.
Here is the exact question. See how you go!
Keith is very upset. A lot of buttons on his calculator are not working. In fact only the 1, 3 and 5 numerals work. However, the “division”, the “equals” and the “decimal point” buttons also work. The teacher asks Keith’s class to find different ways of getting the answers 1 to 20 on a calculator. Help Keith get all the answers on his broken calculator.