Largest Even

How do you know whether a number is even?

To start with, the interactivity below gives you one random digit.
Your task is to find the largest possible two-digit even number which uses the computer's digit, and one of your own.

Have a go several times.

How are you deciding which digit to choose?

Can you decribe a strategy that means your first 'guess' is always correct?

Clicking on the purple cog allows you to change the settings.

For a follow-on challenge, choose an odd two-digit target number (select 'Even False' in the settings).

How are you deciding which digit to choose now?

Can you decribe your new strategy so your first 'guess' is always correct?

You can explore the settings further to change:

• the number of digits in your target number
• the number of digits provided by the computer.

Let us know how your settings change your strategy.