ADDITION AND SUBTRACTION WITHIN 1,000 WITH WORD PROBLEMS TO 100
2.NBT.B.7: Add and subtract within 1000, 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. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
2.NBT.B.7.1: Use estimation strategies to make reasonable estimates in problem solving. CA
2.NBT.B.8: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
2.NBT.B.9: Explain why addition and subtraction strategies work, using place value and the properties of operations.