Sally has a collection of 35 rugby cards. She loses 18 of these. How many does she have left? |
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Student: Thirty five takeaway twenty is fifteen. Fifteen plus two makes seventeen. |
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Students at the Advanced Additive stage are learning to choose appropriately from a repertoire of part-whole strategies. They see numbers as whole units in themselves but also understand that “nested” within these units is a range of possibilities for subdivision and recombining. |
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