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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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— — + +
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What is 5 – (-6) ? + + + + + + — — — — — — ++ ++++ ++++ ++ ———— ——— + + + + + + The Answer is 11.
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What is 3 - 6 ? + + + — — — ++ +++ +++ —— — — + + + The Answer is -3.
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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.
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But why does a negative times a negative equal a positive? -4 3 = -12 -4 2 = -8 -4 1 = -4 -4 0 = 0 -4 -1 = ? The Answer is 4. So a negative times a negative is 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…
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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
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The World’s Tallest Building http://img.dailymail.co.uk/i/pix/2007/07_02/WorldsTallestD M_468x525.jpg How much taller is The Burj Dubai compared to The Empire State Building? Answer: 512 – 381 = 131 meters
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The U.S. National Debt U.S. N ATIONAL D EBT C LOCK 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
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Why Do I Need to Know This? (Motivation and Real World Applications) http://www.labsafety.com/images/xl/Weather- Thermometer-40-to-LSS_i_LBM37561Z.jpg What is the difference between the lowest and the highest temperature reading on the thermometer? Answer: 120 – (-40) = 160°F
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Above and Below Sea Level http://www.treehugger.com/mariana%20trench.jpg http://www.thetravelpeach.com/asia- vacations/everest-mount.jpg Mariana Trent -10,916 Mount Everest 29,035 What is the difference between the highest point above sea level and the lowest point below sea level? Answer: 29,035 – (-10,916) = 39,951
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