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Odd Tic Tac

An odd version of tic tac toe

Largest Even

Stage: 1 Challenge Level: Challenge Level:1

I have a pile of nine digit cards numbered $1$ to $9$.
 
I take one of the cards.  It is the $3$.
 
Which card would you choose so you could make the largest possible two-digit even number with the two cards?
 
We put the cards back in the pile.  This time, I choose the $6$. Which card would you choose this time to make the largest possible two-digit even number?

Have a go at this with a partner.  One of you chooses the first digit from the set of cards.  The second person then chooses a card to make the largest possible two-digit even number. You can then swap over.
 
Try it several times so you are sure you have a good method. Talk about your ideas with your partner so you agree together on a 'best' method.
 
How would your strategy change if you had to make the largest two-digit odd number?
 

If you don't have a partner to work with, you could use the interactivity below.  The computer selects one digit at random.   You must then choose a digit to make the largest possible two-digit even number or largest possible two-digit odd number.


Enter the biggest two-digit number you can think of that uses the digit: