Practice Problems — Set 20

2.NBT.B.9 · Explain why addition and subtraction strategies work, using place val…

Print and write your answers. Use diagrams to show thinking.

Warm-up

1. Talk through today's focus: Explain why addition and subtraction strategies work, using place val… 2. Try one oral example together before writing. 3. Use the diagram to explain your thinking.

_See printable PDF for diagram._

Written practice

1. Write the value of the underlined digit in 340: ___ 2. 50 = ___ tens + ___ ones 3. Expanded form: 60 = ___ + ___ 4. Which is greater: 45 or 52? ___ 5. Write the numeral: 7 tens and 5 ones → ___ 6. Round 67 to the nearest ten: ___ 7. Explain your thinking for set 20 in one sentence. 8. Create your own problem for 2.NBT.B.9.

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More written practice

1. Apply Explain why addition and subtraction strategies work, using place val… (item 9, set 20): show your work. ___ 2. Apply Explain why addition and subtraction strategies work, using place val… (item 10, set 20): show your work. ___ 3. Apply Explain why addition and subtraction strategies work, using place val… (item 11, set 20): show your work. ___ 4. Apply Explain why addition and subtraction strategies work, using place val… (item 12, set 20): show your work. ___ 5. Apply Explain why addition and subtraction strategies work, using place val… (item 13, set 20): show your work. ___ 6. Apply Explain why addition and subtraction strategies work, using place val… (item 14, set 20): show your work. ___

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Patterns and rules

1. Each place is ten times the place to its right. 2. Compare from the largest place first. 3. Expanded form shows the value of each digit.

_See printable PDF for diagram._

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Stretch

1. Create your own 2.NBT.B.9 question for a parent to solve. 2. Explain your method in two sentences.

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Parent tip: Use base-ten blocks or place-value charts