Midcontinent Research for Education and Learning
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Common Core Mathematics K2
Cluster
Use place value understanding and properties of operations to add and subtract.
Grade 1
1.NBT.4.
Add within 100, including adding a twodigit number and a onedigit number, and adding a twodigit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding twodigit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
1.NBT.5.
Given a twodigit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
1.NBT.6.
Subtract multiples of 10 in the range 1090 from multiples of 10 in the range 1090 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.