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Home / Teaching Resources / Grade 1 / Standards for Mathematical Practice / Operations & Algebraic Thinking / Understand and apply properties of operations and the relationship between addition and subtraction / CCSS.MATH.CONTENT.1.OA.B.4
Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8. (View this topic on www.corestandards.org )