Postman Stories for Multiplying Integers

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# Postman Stories for Multiplying Integers - PowerPoint PPT Presentation

Postman Stories for Multiplying Integers. What do you think?. Should a check be represented by a positive number, or a negative one?. What do you think?. Should a check be represented by a positive number, or a negative one?

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### Postman Stories for Multiplying Integers

What do you think?
• Should a check be represented by a positive number, or a negative one?
What do you think?
• Should a check be represented by a positive number, or a negative one?
• Should a bill be represented by a positive number, or a negative one?
Remember . . .
• Checks are positive numbers.
• A check for \$3 may be written as 3.
• Bills are negative numbers.
• A bill for \$7 may be written as -7.
What do you think?
• If the postman brings you mail, do you have more mail than before, or less?
• Should this be a positive number, or a negative one?
• If the postman takes away mail, do you have more mail than before, or less?
• Should this be a positive number, or a negative one?
Remember . . .
• If the postman brings you mail, it is represented by a positivenumber.
• If he brings you 6 pieces of mail, write 6.
• If the postman takes away mail, it is represented by a negative number.
• If he takes away 10 pieces of mail, write -10.
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a check for \$10. How would you write this number?
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a check for \$10. How would you write this number?
• What multiplication problem represents this situation?
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a check for \$10. How would you write this number?
• What multiplication problem represents this situation?

5x10 = ?

Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a check for \$10. How would you write this number?
• What multiplication problem represents this situation?

5x10 = 50

Check It!

5x10 = 50

• Does the answer +50 make sense? Did you gain \$50 when he brought you 5 checks for \$10 each?
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a bill for \$10. How would you write this number?
Let’s practice!
• Suppose the postman brings you 5 pieces of mail. How would you write this number?
• Suppose each piece of mail was a bill for \$10. How would you write this number?
• What multiplication problem is this?
• What’s the answer to that multiplication problem?
Let’s Practice!
• The postman brought you 5 pieces of mail.
• Each piece of mail was a bill for \$10.

5X-10 = -50

Does it make sense?
• The postman brings you 5 pieces of mail.
• Each piece of mail is a bill for \$10.
• You lost \$50. This is the number -50!
• Equation:

5X-10 = -50

• You lost \$50. This is the number -50!
Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• How can we express this mathematically?
Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• How can we express this mathematically?

(Write an expression!)

Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• How can we express this mathematically?

(Write an expression!)

-5X10 = ?

Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• Solution:

-5X10 = -50

Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• Write a math problem for this situation

and solve it.

Let’s Practice
• When you paid your bills, the postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.

-5 x10 = -50

Does it make sense?
• The postman took away 5 pieces of mail.
• Each piece of mail was a check for \$10.
• Equation:

5X-10 = -50

• You have \$50 less than before. This is the answer: -50!
Last Practice
• The postman takes away 5 pieces of mail.
• Each piece of mail is a bill for \$10.
Last Practice
• The postman takes away 5 pieces of mail.
• Each piece of mail is a bill for \$10.
• Write an equation for this.
Last Practice
• The postman takes away 5 pieces of mail.
• Each piece of mail is a bill for \$10.
• Equation:

-5X-10 = 50

Does It Make Sense?
• The postman takes away 5 pieces of mail.
• Each piece of mail is a bill for \$10.
• Equation:

-5X-10 = 50