The student must be able solve problems by understanding number relationships of 10 more and 10 less. They must be able to explain how they solved the problem and how they know they are correct.
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1.5 Algebraic reasoning. The student applies mathematical process standards to identify and apply number patterns within properties of numbers and operations in order to describe relationships. The student is expected to:
(C) use relationships to determine the number that is 10 more and 10 less than a given number up to 120