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Challenge Okta or a friend in a duel! Collect cards with the specified sum, and you win. But you better do it before your opponent does!

Choose the number of cards and type of numbers. Can you figure out a way to guarantee your win? We hope so!

Practice your strategy by playing against Okta. We hear she’s great competition. Okta learns as you do. She gets smarter each time you beat her!

This app was developed by Illuminations. It is also available as an online interactive along with accompanying lesson plans and guides. Visit illuminations.nctm.org to access these and more!