Process versus The Reason Why
1. Because Subtraction Means to Take
Away
2. Because Multiplication and Division of
Integers Follow a Pattern
3. Because it Makes Sense
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What is 5 – (-6) ?
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The Answer is 11.
What is 3 - 6 ?
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The Answer is -3.
Why does a positive times a
negative equal a negative?
4 • 3 = 12
4•2= 8
4•1=4
4•0=0
4 • -1 = ?
The Answer is -4.
So a positive
times a negative
is a negative.
But why does a negative times a
negative equal a positive?
Well, knowing a
positive times a
negative is a
negative, also
means that a
negative times a
positive is a
negative, so again…
-4 • 3 = -12
The Answer is 4.
-4 • 2 = -8
-4 • 1 = -4
-4 • 0 = 0 So a negative
times a negative
is a positive.
-4 • -1 = ?
Floors on Elevators
This is an elevator panel with NEGATIVE
numbers.
How far many floors have you gone up if
you start at the lowest floor and go to the
highest floor?
(1)Set up the expression
(2)Explain your reasoning
(3)Solve the problem
Answer: 17-(-2) =
19 floors
The World’s Tallest Building
How much taller is
The Burj Dubai
compared to The
Empire State
Building?
Answer: 512 – 381 =
131 meters
http://img.dailymail.co.uk/i/pix/2007/07_02/WorldsTallestD
M_468x525.jpg
The U.S. National Debt
U.S. NATIONAL DEBT CLOCK
The Outstanding Public Debt as of 09 Jan 2010 at 01:30:59 PM
GMT is:
http://www.brillig.com/debt_clock/
If the government taxed each American $40, 068.00,
approximately how many Americans would it
require to pay to off our National Debt?
Answer: -12,287,322,881,897 ÷ -40,068.00 ≈ 306,666,778
Americans
Why Do I Need to Know This?
(Motivation and Real World Applications)
What is the difference
between the lowest
and the highest
temperature reading
on the thermometer?
Answer: 120 – (-40)
= 160°F
http://www.labsafety.com/images/xl/WeatherThermometer-40-to-LSS_i_LBM37561Z.jpg
Above and Below Sea Level
What is the
difference between
the highest point
above sea level and
the lowest point
below sea level?
Mount Everest
29,035
http://www.thetravelpeach.com/asiavacations/everest-mount.jpg
Mariana Trent
-10,916
Answer: 29,035 – (-10,916) = 39,951
http://www.treehugger.com/mariana%20trench.jpg