Calculator battle

For this activity, you and your child each need a calculator.

The idea of this game is to ‘steal’ your opponent’s number by asking a series of questions.

To start, without showing each other, you both need to type in a 2-digit number into your calculator (e.g. you choose 52, and your child chooses 34).

You go first and ask (with surprising intuition), ‘Is the digit 3 anywhere in your number?’ They would say, ‘Yes, I have a 3 and it is worth 3 tens or 30’.

They subtract 30 from their number and you add 30 to your number.

Your screen would now show 82 and your child’s would show 4.

Now it’s your child’s turn to ask you for a number.

If they ask you for a 7, for example, you say ‘no’, and it’s back to your turn.

This game could go on for ever – so maybe, the winner is the last person to have zero showing on their calculator.

Or the winner is the person with the largest number after ten goes.

To extend this task, you can use 3-digit numbers.