# 1-5 Mental Math Warm Up Problem of the Day Lesson Presentation

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1-5 Mental Math Warm Up Problem of the Day Lesson Presentation
Course 1 Warm Up Problem of the Day Lesson Presentation

1-5 Mental Math Warm Up Find each sum or product. 1. 17 + 15
Course 1 1-5 Mental Math Warm Up Find each sum or product. 3. 8(24) 4. 7(12) 5. 3(91) 6. 6(15) 32 68 192 84 273 90

1-5 Mental Math Problem of the Day
Course 1 1-5 Mental Math Problem of the Day Determine the secret number from the following clues: The number is a multiple of 5. It is divisible by 3. It is less than 200. Its tens digit equals the sum of its other two digits. 165

1-5 Mental Math Learn to use number properties to compute mentally.
Course 1 1-5 Mental Math Learn to use number properties to compute mentally.

Insert Lesson Title Here
Course 1 1-5 Mental Math Insert Lesson Title Here Vocabulary Commutative Property Associative Property Distributive Property

Course 1 1-5 Mental Math Mental math means “doing math in your head.”

COMMUTATIVE PROPERTY (Ordering)
Course 1 1-5 Mental Math COMMUTATIVE PROPERTY (Ordering) Words Numbers You can add or multiply numbers in any order. = 15  2 = 2  15

ASSOCIATIVE PROPERTY (Grouping)
Course 1 1-5 Mental Math ASSOCIATIVE PROPERTY (Grouping) Words Numbers When you are only adding or only multiplying, you can group any of the numbers together. (17 + 2) + 9 = 17 + (2 + 9) (12  2)  4 = 12  (2  4)

Course 1 1-5 Mental Math Additional Example 1A: Using Properties to Add and Multiply Whole Numbers A. Evaluate Look for sums that are multiples of 10 Use the Commutative Property. Use the Associative Property to make groups of compatible numbers. (17 + 3) + (5 + 15) Use mental math to add. 40

Course 1 1-5 Mental Math Additional Example 1B: Using Properties to Add and Multiply Whole Numbers B. Evaluate 4  13  5. Look for products that are multiples of 10 4  13  5 13  4  5 Use the Commutative Property. Use the Associative Property to group compatible numbers. 13  (4  5) 13  20 Use mental math to multiply. 260

1-5 Mental Math Try This: Example 1A A. Evaluate 12 + 5 + 8 + 5.
Course 1 1-5 Mental Math Try This: Example 1A A. Evaluate Look for sums that are multiples of 10 Use the Commutative Property. Use the Associative Property to make groups of compatible numbers. (12 + 8) + (5 + 5) Use mental math to add. 30

1-5 Mental Math Try This: Example 1B B. Evaluate 8  3  5.
Course 1 1-5 Mental Math Try This: Example 1B B. Evaluate 8  3  5. Look for products that are multiples of 10 8  3  5 3  8  5 Use the Commutative Property. Use the Associative Property to group compatible numbers. 3  (8  5) 3  40 Use mental math to multiply. 120

DISTRIBUTIVE PROPERTY
Course 1 1-5 Mental Math DISTRIBUTIVE PROPERTY Words Numbers When you multiply a number times a sum, you can find the sum first and then multiply, or multiply by each number in the sum and then add. 6  (10 + 4) = 6  14 = 84 6  (10 + 4) = (6  10) + (6  4) = =

Course 1 1-5 Mental Math When you multiply two numbers, you can “break apart” one of the numbers into a sum and then use the Distributive Property. Break the greater factor into a sum that contains a multiple of 10 and a one-digit number. You can add and multiply these numbers mentally. Helpful Hint

Additional Example 2A: Using the Distributive Property to Multiply
Course 1 1-5 Mental Math Additional Example 2A: Using the Distributive Property to Multiply Use the Distributive Property to find the product. A. Evaluate 6  35. “Break apart” 35 into 6  35 = 6  (30 + 5) Use the Distributive Property. = (6  30) + (6  5) Use mental math to multiply. = = Use mental math to add.

Additional Example 2B: Using the Distributive Property to Multiply
Course 1 1-5 Mental Math Additional Example 2B: Using the Distributive Property to Multiply Use the Distributive Property to find the product. B. Evaluate 9 x 87. “Break apart” 87 into 9  87 = 9  (80 + 7) Use the Distributive Property. = (9  80) + (9  7) Use mental math to multiply. = = Use mental math to add.

1-5 Mental Math Try This: Example 2A
Course 1 1-5 Mental Math Try This: Example 2A Use the Distributive Property to find the product. A. Evaluate 4 x 27. “Break apart” 27 into 4  27 = 4  (20 + 7) Use the Distributive Property. = (4  20) + (4  7) Use mental math to multiply. = = Use mental math to add.

1-5 Mental Math Try This: Example 2B
Course 1 1-5 Mental Math Try This: Example 2B Use the Distributive Property to find the product. B. Evaluate 6  43. “Break apart” 43 into 6  43 = 6  (40 + 3) Use the Distributive Property. = (6  40) + (6  3) Use mental math to multiply. = = Use mental math to add.

Insert Lesson Title Here
Course 1 1-5 Mental Math Insert Lesson Title Here Lesson Quiz Evaluate.  5  3 Use the Distributive Property to find each product. 4. 8   15 6. Angie wants to buy 3 new video games. How much will she need to save if each game costs \$27? 50 150 70 96 90 \$81

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