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Do Now 11/15/11 Take out your HW from last night. Copy HW in your planner. Text p. 102, #10-40 evens, #42, 43, 48, & 49 Text p. 106, #10-44 evens In your journal, estimate an answer to the following situation. Potato salad costs $0.99 per pound at the deli counter. About how much do you think 6.5 pounds of potato salad will cost? Homework Text p. 102, #10-40 evens, #42, 43, 48, & 49 10) 39.05 12) 16.917 14) 15.33 16) 9.071 18) 2.24 20) 12.79 22) 4.47 24) 31.15 26) 8.25 minutes 28) -0.338 30) -17.361 32) -125.55 34) 48.46 36) 30.623 38) -2.6 40) 1,642.5 miles 42) 1.6 °F 43) 1915 48) B 49) G Objective SWBAT multiply decimals Section 3-2 Multiplying 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. Find the product. 3.06 x 1.4 1224 +3060 4284 4.284 3.06 x 1.4 2 decimal places 1 decimal place How many decimal places are in each number? How many decimal places are in the sum of both numbers? 3 decimal places will then be in the product! Do you see a pattern? How many decimal places are in the factors? 12 x4 48 1.2 x 4 4.8 How many decimal places are in the products? 0.12 x 0.4 48 000 0.048 Practice 1) 1.46 x 0.02 1) 1.46 x 0.02 0.0292 2) 3.04 x 1.6 2) 3.04 x 1.6 1824 _+3040 4.864 “Multiplying Integers” 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 Estimating Round each decimal to the nearest integer than find the product. 7.2(-4.36) -28 -3.3(-3.3) 9 -11.3 x 7.76 -88 -7.3(-6.72) 49 Find the product. -2.78 x 0.8 -2.224 -2224 -2.78 · 0.8 2 decimal places 1 decimal place How many decimal places are in each number? How many decimal places are in the sum of both numbers? 3 decimal places will then be in the product! Find the product. 0.014 x -16 0084 +0140 -0.224 -0224 -16 x 0.014 3 decimal places 0 decimal places How many decimal places are in each number? How many decimal places are in the sum of both numbers? 3 decimal places will then be in the product! “Real-Life” On average, Americans eat 0.25 lb of peanut butter per month. How many pounds of peanut butter are eaten by approximately 302 million Americans living in the United States per month? 302 x 0.25 1510 6040 75.50 million pounds of peanut butter are eaten by Americans each month 24 Homework Text p. 106, #10-44 evens