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Do Now 12/2/13

Do Now 12/2/13. Copy HW in your planner. Text p. 116, #1-19 odds Benchmark Test Chapters 1,2,3, & 11 Wednesday and Thursday. Objective. SWBAT review adding, subtracting, multiplying, and dividing decimals. ADDITION & SUBTRACTION REVIEW. Section 2.2 “Adding Integers”. Remember this?.

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Do Now 12/2/13

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  1. Do Now 12/2/13 • Copy HW in your planner. • Text p. 116, #1-19 odds • Benchmark Test Chapters 1,2,3, & 11 Wednesday and Thursday.

  2. Objective • SWBAT review adding, subtracting, multiplying, and dividing decimals

  3. ADDITION & SUBTRACTION REVIEW

  4. Section 2.2 “Adding Integers” Remember this? 35 + 18 -35 + (-18) |35| = 35 |18| = 18 |-35| = 35 |-18| = 18 35 + 18 = 53 - 35 + 18 = 53

  5. Section 2.2 “Adding Integers” Remember this? -35 + 18 |-35| = 35 |18| = 18 - 35 – 18 = 17 Because 35 has a greater absolute value than 18 the answer is “negative”.

  6. Section 2.3 “Subtracting Integers” Remember this? • When subtracting two integers, ADD the OPPOSITE of the second number to the first. Instead of subtracting ADD the OPPOSITE!! 8 – 5 = Do the “OPP-OPP” “Opposite-Opposite” ADD the OPPOSITE 3 8 + (-5) =

  7. Section 3-1Adding & Subtracting Decimals Add & subtract decimal numbers by lining up the decimal point. HUNDREDTHs TENTHS Ones 1.2 + 0.87 1.2 0 Use a zero as a placeholder so that both numbers are in the same place value +0.87 2.07

  8. 32.7 + (-62.82) |32.7| = 32.7 |-62.82| = 62.82 HUNDREDTHs TENTHS Ones Tens 62.82 – 32.7 62.82 Use a zero as a placeholder so that both numbers are in the same place value. – 32.7 0 Because 62.82 has a greater absolute value than 32.7 the answer is “negative”. - 30.12

  9. -5.23 – 9.1 Add the Opposite !!! -5.23 + (-9.1) HUNDREDTHs TENTHS Ones To add two integers with the SAME signs, find the sum of their absolute values. Use the sign of the two integers 5.23 Use a zero as a placeholder so that both numbers are in the same place value. + 9.1 0 - 14.33

  10. “Real-Life” During one month in the United States, 492.23 million commuter trips were taken on buses, and 26.331 million commuter trips were taken on light rail. How many more trips were taken on buses than on light rail? 492.230 – 26.331 465.899 million more trips were taken on buses than on light rail

  11. MULTIPLICATION REVIEW

  12. “Multiplying Integers” Remember this? Rule #1 The product of two integers with the same sign is always POSITIVE! 8 x 3 = 24 -8 · (-7) = 56 Rule #2 The product of two integers with different signs is always NEGATIVE! -6 x 3 = -18 8(-4) = -32

  13. Section 3-2Multiplying Decimals To multiply decimals, multiply as you would integers. To place the decimal point in the product count the number of decimal places in each factor. The product will have the same number of decimal places as the sum of the decimal places in the factors.

  14. Find the product. -2.78 · 0.8 -2.78 2 decimal places How many decimal places are in each number? x 0.8 1 decimal place -2.224 -2224 How many decimal places are in the sum of both numbers? 3 decimal places will then be in the product!

  15. 0.014 Find the product. -16 x 0.014 3 decimal places How many decimal places are in each number? x -16 0 decimal places 0084 How many decimal places are in the sum of both numbers? +0140 -0.224 -0224 3 decimal places will then be in the product!

  16. “Real-Life” The average snowfall in Howell, NJ is 18.55 inches per winter. What is the total amount of snowfall in inches expected over the next 2.5 years? 18.55 x 2.5 9275 37100 46.375 Inches of snowfall expected in the next 2.5 years

  17. DIVISION REVIEW

  18. Section 3-3 “Dividing Decimals” How do you divide two decimal numbers 0.6 ÷ 0.3 or 0.3 0.6 divisor By multiplying both numbers by the same power of ten, you can make the divisor an integer. Dividing by an integer is much easier than dividing by a decimal. 2 0.3 0.6 Multiply both numbers by 10 3 6

  19. Find the quotient of -0.875 ÷ (-0.25) Multiply both numbers by 100 to make the divisor an integer 0.25 0.875 25 87.5 3 5 Move the decimal point straight up, then divide as you normally would. 25 87 . 5 75 The quotient of two integers with the same sign is always POSITIVE! 12 125 Finished

  20. “Real-Life” If Sandy and her family used 14.95 gallons of gas to drive 358.8 miles, how many miles per gallon did the car get? Multiply both numbers by 100 to make the divisor an integer 14.95 358.8 24 1495 35880 The car got 24 miles per gallon

  21. 24 Homework Text p. 116, #1-19 odd

  22. Joey is in the process of buying a new vehicle. He has narrowed his options down to 2 choices. Which vehicle gets better gas mileage (mpg) and by how much? 6.8 gallons of gas can go 164.9 miles 2.5 gallons of gas can go 48.5 miles 19.4 24.25 miles per gallon miles per gallon 2.5 48.5 6.8 164.9 24.25 The car gets 4.85 more miles per gallon of gasoline than the SUV. – 19.4 0 4.85

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