Transcript Commutative Property

Commutative
Property
Lesson 3.1:
Commutative Property of
Multiplication
• Write two multiplication and two division sentences
for this array.
Commutative Property of
Multiplication
• Write two multiplication and two division sentences
for this array.
Commutative Property of
Multiplication
• Write two multiplication and two division sentences
for this array.
Commutative Property of
Multiplication
• Write two multiplication and two division sentences
for this array.
Application Problem
• Geri brings 3 water jugs to her soccer game to
share with teammates. Each jug contains 6 liters of
water. How many liters of water does Geri bring?
• Draw a tape diagram and write a number
sentence to solve the problem.
Problem 1
• Which tape diagram represents the Application
Problem? How do you know?
Problem 1
• Draw both tape diagrams in your notebook. Write a
multiplication sentence for each.
• How are the multiplication sentences related?
• They use the same numbers.
• Both have a product of 18. They use the same
factors, but in a different order. The product is the
same.
Problem 1
• This is an example of the commutative property that
we studied in Unit1. What does this property tell us
about the product and its factors?
• Even if the order of the factors changes, the
product stays the same!
Problem 1
Earlier in the year we learned our threes.
If we know 3 × 6, what other fact do we know?
6×3
What is the product of both 3 × 6 and 6 × 3?
To show that 3 × 6 and 6 × 3 equal the same
amount, we can write 3 × 6 = 6 × 3.
• Using the commutative property as a strategy, we
know many more facts than just the ones we’ve
practiced!
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Problem 1
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Draw a tape diagram to show 2 × 7.
What is the product of 2 x 7?
Draw a tape diagram to show 7 × 2.
What is the product of 7 x 2?
How does knowing 2 x 7 help you know 7 x 2?
2x7=7x2
This is an example of the Commutative Property of
Multiplication.
Problem 1
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Draw a tape diagram to show 5 eights.
What is the product of 5 eights?
Draw a tape diagram to show 8 fives.
What is the product of 8 fives?
How does knowing 5 x 8 help you know 8 x 5?
5x8=8x5
This is an example of the Commutative Property of
Multiplication.
Problem 2
• Multiplication Chart
Row 3
Problem 2
• Multiplication Chart
Problem 2
We know the shaded facts.
Practice
• Complete the chart. Each bag contains 7 apples.
Practice
Use the array to write two different multiplication
sentences.
Practice
Complete the equations.
• a. 2 sevens = ________ twos
= ________
• b. 3 ________ = 6 threes
= ________
• c. 10 eights = 8________
= ________
• d. 4 × _______ = 6 × 4
= ________
Practice
Complete the equations.
• e. 8 × 5 = ________ × 8
= ________
• f. _______ × 7 = 7 ×_______
= ________
• g. 3 × 9 = 10 threes – _______ three
= ________
• h. 10 fours – 1 four = _______ × 4
= ________
Practice
Complete the equations.
• i. 8 × 4 = 5 fours + _______ fours
= ________
• j. _______fives + 1 five = 6 × 5
= ________
• k. 5 threes + 2 threes = _____× _____
= ________
• l. ______ twos + ______ twos = 10 twos
= ______