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Page 1: 1.02a distributive property

2 x 2 digit Multiplication

We are going to learn:

1.02a – 2 x 2 digit multiplication

1.02c – Different multiplication strategies

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We are also going to use the

Distributive Property

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Review

• Commutative Property – Changing the order of the factors doesn’t change the product

• Examples?

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Review

• Identity Property of Multiplication – Any number times one is that same number.

• Identity Property of Addition – Any number plus zero is that same number.

• Examples?

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• Associative Property - Changing the grouping of the numbers, doesn’t change the answer.

• Remember:

8 + (9 +7) = (8 + 9) + 7

(3 x 4) x 5 = 3 x (4 x 5)

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Let’s Try Something New!

• Solve the following expression:

3 x (4 + 7)

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• Use the distributive property to solve the expression another way…– Distribute or share the 3 with the 4 and 7.

Check it out:

3 x (4 + 7) = (3 x 4) + (3 x 7)

- Solve the parentheses and then add them together! The answer is the same.

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Example: 5 x (6 + 4)

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Different Way

• What if one of the numbers isn’t broken up already?

• We can use the distributive property with more complicated multiplication. We break up one number to make the multiplication easier.

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Let’s Try: 20 x 56

I don’t mind multiplying with 20 because it has a zero, but 56 is

more difficult! So…I am going to break up 56

into 50 and 6.

20 x 56 = (20 x 50) + (20 x 6)

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Another example:

Let’s break up – 11 x 17

Which number should we break apart? Why?

(10 x 11) = 110

17 ( 7 x 11) = + 77

x 11 187

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36 x 22

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Distributive Property24 x 55

1. Pick one of the numbers to break apart 242. Break it apart by:

the value of the tens place – 20 the value of the ones place – 4.

3. Multiply each piece x the second number – 55.(20 x 55) + (4 x 55)

4. Add the products together.

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• Now – you try some examples in your journal.

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• Solve the following problems by the breaking apart the underlined number.

47 x 30 63 x 41

12 x 52 23 x 29