 # The Big One Years 2 - 8 A game for two players using the same calculator.

### Preparation

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

### How To Play The Big One

 Player A is the 'hider'. Player B is the 'finder'. Player A thinks of a mystery number and 'hides' it in the calculator by entering ũ [mystery number] = . Note: You may want to begin the game by limiting the choice to, say, 2-digit numbers. If clear is not pressed, the calculator is now set up to divide by the mystery number whenever = is pressed. Player B has to find the mystery number by entering [guess number] = . Note: Some calculators show a ũ sign when [guess number] is pressed to remind about the operation which has been entered. If the guess is correct, a special number (the Big 1) will appear on the screen. If the guess is not correct, it will provide information for the next guess. Without pressing clear Player B continues to enter [guess number] = until the Big One appears. Keep a record of each guess in your journal. It is also useful to comment on whether the guess was too big or small. Score one point for each try. Players swap roles. Winner is the player with the lower total score after, say, three (3) or five (5) rounds. Player A pressed ũ 3 = to hide the mystery number and leave a zero (0) on the screen. Player B then guessed 6 =. The calculator used the ũ 3 stored in its 'brain' to get the answer 2.
Have fun exploring The Big One.

We suggest it is used at least three (3) times a week for about fifteen (15) minutes over several weeks.

### Hunting For Whole Numbers

• Teach the calculator to divide by 3, or 7 or any other number. Let's pretend you chose 5.
• In your journal write today's date at the top of the page in the middle and write the calculator's number (ũ 5) under the date.
• Write DO at the top of the left column and DON'T at the top of the right column.
• Your challenge is to find seven (7) numbers that give a whole number answer when you press [guess number] = .
• When you find one, write it on the DO side like this.
Example:
If you guessed 10 and the calculator's number was (ũ 5) the screen answer would be 2.
In your journal on the DO side you write 10 ũ 5 = 2.
Put a box around the 10.
• If you make a guess that doesn't give a whole number answer you do the same thing on the DON'T side.
• The aim is to find seven numbers that work without having any DON'T answers.

### Hunting For Patterns

• Teach your calculator to divide by any number you want. Keep it single digit to start with.
• Now press [guess number] = and write the equation in your journal.
• Do this 15 - 20 times. Each equation is a piece of data.
• Organise your pieces of data to hunt for any patterns?
• Perhaps there are some gaps in your data. What do you need to do?

### Just Before You Finish

For this part you need your maths journal and your Working Like A Mathematician page.
• Write at least five (5) ways you are working like a mathematician when you are The Big One activities.  