Breakdown!

Years 2 - 8
In these problems the calculator is being used to stimulate thought about alternative ways of creating given numbers, or alternative ways of achieving an operation. Class discussions based on the students' suggestions contribute naturally to growth in number sense. There are many forms of these problems and teachers frequently find that they result in the children doing many more 'arithmetic' problems than would be achieved in the same time using a text or worksheet.

Example 1:

The 7, 8 & 9 keys are broken. They do not work when pressed, so there is no point pressing them.
  • How could these problems be worked out on the calculator?

625 + 292 ... 138 + 80 ... 89 x 19 ... 875 - 125

  • Is there only one answer in each case?
  • Which way uses the fewest keystrokes?

Example 2:

Suppose the only working keys are:

[3] [8] [x] [-] [=]

  • Show how you can still get all the answers from 1 to 10.
  • What is the least number of key strokes (button presses) it takes to get each one?
  • Which of your solutions can you demonstrate using Poly Plug?

Calculating Changes ... is a division of ... Mathematics Centre