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Unit 1: Number Sense
Minds On
Solve for “x” in the following equations:
a) 5x = 35
b) 3x – 6 = 12
Unit 1: Number Sense
Review: Operations with Negative Numbers
Learning Goals:
I can add and subtract negative numbers
I can multiply and divide negative numbers
Unit 1: Number Sense
Review: Operations with Negative Numbers
Multiplying and Dividing
• If the signs are the answer will be positive.
• If the sign are the answer will be negative.
Unit 1: Number Sense
Review: Operations with Negative Numbers
Multiply or Divide
Unit 1: Number Sense
Review: Operations with Negative Numbers
In Summary:
• A Positive multiplied or divided by another Positive results in a:
• A Positive multiplied or divided by a Negative results in a:• A Negative multiplied or divided by a Positive results in a:• A Negative multiplied or divided by another Negative
results in a:
Unit 1: Number Sense
Review: Operations with Negative Numbers
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: =
Example: =
Example: =
Unit 1: Number Sense
Review: Operations with Negative Numbers
Adding and Subtracting:Step One: If there are two signs beside each
other, reduce them to one sign• Example: +3 + (-6)
Step Two: think of the signs as representing teams (a positive team and a negative team)
Step Three: Check who won, and by how much• The winning team
determines the sign of the answer (+ or - )•How much they won by
determines the number of the answer
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: -5- (-8)
Step One: Reduce to one sign
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: -5 + 8
Step Two: Think of Teams
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: -5 + 8
Step Three: Who won? By how much?
Negative team has 5
Positive team has 8
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: +5- (+6)Reduce to one sign
+5 - 6Who won?Negative TeamBy How much?1
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: +5 – (-1)
Positive team had to win because the negative team didn’t show up
Unit 1: Number Sense
Review: Operations with Negative Numbers
Example: -3 + -2
Negative team had to win because the positive team didn’t show up
Unit 1: Number Sense
Review: Operations with Negative Numbers
Lisa says that if you add two opposite integers their sum is always zero. Is Lisa correct?
Unit 1: Number Sense
Review: Operations with Negative Numbers
Janet says that two negatives makes a positive? Is she correct? Look at all four operations.
Unit 1: Number Sense
Review: Operations with Negative Numbers
Sam says that if you subtract any two negative numbers the difference is always negative. Is he correct?
Unit 1: Number Sense
Review: Operations with Negative Numbers
More Examples!
1) (+4)(-15) 2) 15 – (-3) 3) (-6)
4) (+4) 5) 0 + (-8) 6) 3 – (-7)
7) (-8) – 14 8) (+9) – 22 9) 4 – (-5) + (16)
Unit 1: Number Sense
Review: Operations with Negative Numbers
Practice
Addition/Subtraction: Read pg. 18 Ex #1 and #2
Complete #1, 3, 5
Multiplication/Division: Read top of page 19
Complete #1 - 4
