Using Common Core State Standards for Mathematics (CCSS-M), learn to mentally add 10 or 100 to a given number 100-900, and mentally substract 10 or 100 from a given number 100-900.
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Using Common Core State Standards for Mathematics (CCSS-M), learn to mentally add 10 or 100 to a given number 100-900, and mentally substract 10 or 100 from a given number 100-900.
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