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** Practice Addition and Subtraction.**

**(A). Finding Sum and Differences.**

- Attempt the problems on paper before checking the answers.
- Check the Hint boxes to see the explanations.
- Click the white square box at the left bottom for a new problem.
- Practice with harder problems by moving the slider to the right. You might have to high light it and use the forward arrow key on your key board.

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**(B). Matching Practice.**

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**Add by Creating Base-ten Blocks.**

The applet below has tools that create each of the base-ten blocks. You need to decide the value of each block before you begin.

- Select a Block tool, and then click on the screen to place it.
- Click on the Move tool (the arrow) when you are done choosing blocks.
- Subtract by deleting with the delete tool (the trash can), not by crossing out.

Compute each sum below by drawing base-ten diagrams on the applet to help you.

(1). 0.11 + 0.005

(2). 0.209 + 0.01

(3). 10.2 + 1.1456

(4). 0.2 + 0.05

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**Subtract by Creating Base Ten Blocks.**

Find each difference. If you get stuck, you can use the applet below to represent each expression and find its value.

Explain how you got your answer in each case.

(1). 0.3 – 0.05

(2). 2.1 – 0.4

(3). 1.03 – 0.06

(4). 0.02 – 0.007

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Answer True or False.

Explain your reasoning in each case.

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Andre and Jada drew base-ten diagrams to represent . Andre drew 11 small rectangles. Jada drew only two figures: a square and a small rectangle.

(1). If both students represented the sum correctly, what value does each small rectangle represent?

(2). What value does each square represent?

(3.) Describe a diagram that could represent the sum . OR draw it in the applet below.

Draw a diagram that could represent the sum .

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