Target Range
Years 4 - 9


A calculator game for 2 players using one calculator.

 

This game can be played using any of the four operations (+, -, x, ). Players choose a 'winning zone' or 'target range'. Players also agree on the operation to use for this round. Then they take turns to operate on the calculator to be first to land in the range.

Preparation

  • One calculator (there's one on your phone)
  • Write the title of this challenge and today's date on a fresh page in your maths journal.

Getting Started

In this example the players choose to use multiplication as the challenge operation.
  1. Players agree on a Target Range, such as 370 to 390, and write it down.
    (This is only an example. It can be anything.)
  2. Players also agree on the operation for this round.
  3. Player A enters a start number, eg: 56.
    • All operations will now be 'times' for this round (if times is the operation players have chosen).
  4. Player B guesses a number which he or she thinks will take the display into the Target Range and presses x, 'guess', =.
    • For example Player B might press, x 7, = because they know 7 x 50 = 350.
      The result will be 392.
  5. Player A then guesses the number which will take the 392 into the range and presses x, 'guess', =.
    • For example they might press x, 099, = and the result will be 38808.
  6. In this case Player A wins because their action took the display into the agreed range.
This is one round of the game. Sometimes, depending on how well you estimate, one round might take several tries to land in the range.
The winner scores one point and one game is best of five rounds (or other similar rule).
  1. Use your journal to keep a record of:
    - target range
    - operation
    - guesses
    It is also useful to write comments about your guesses.
Have fun exploring Target Range.

Play a game at least 3 times a week for at least 3 weeks and keep good records as you play.

Variations

  1. The game works with any of the four operations and throws up interesting number sense challenges for each one. For example, when using addition and subtraction negative numbers can arise, and when using division, you might have to divide by a decimal to get a larger answer.
  2. What happens if the Target Range is between two non-whole numbers (perhaps 07 to 09)? ... or the multiplier is a decimal? ... or both?

Just Before You Finish

Look back at your records for Target Range and answer this question in your maths journal.
  • What do you know now that you didn't know when you started Target Range?

 

Answers & Discussion

These notes were originally written for teachers. They have been shared from the Members section of Calculating Changes, which is a division of Mathematics Centre.

Send any comments or photos about this activity and we can start a gallery here.

 

Maths At Home is a division of Mathematics Centre