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Quick Review

Quick Review. Round to the place value of the underlined digit: 1. 3, 5 28 2. 1 3 1,295 3. 2 29,000 4. 9 9 5. Answers: 3,500 130,000 200,000 1,000. Using Estimation Strategies. Section 1-1 (pages 5-9). Estimate or Exact?.

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Quick Review

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  1. Quick Review Round to the place value of the underlined digit: 1. 3, 528 2. 131,295 3. 229,000 4. 995 • Answers: • 3,500 • 130,000 • 200,000 • 1,000

  2. Using Estimation Strategies Section 1-1 (pages 5-9)

  3. Estimate or Exact? Suppose you are writing a news article. Your notes contain some data that may be estimates. For each situation, decide whether you have an estimate or an exact value. Explain your decision. a) The population of Florida is 16,000,000. b) Florida has 25 representatives in the U.S. House of Representatives. Estimate Exact Value Other examples??

  4. Things to Remember… • Estimate a number before you calculate it • Use the symbol which means “approximately equal to”

  5. Estimating a Sum or Difference • At the zoo, you see a Colombian black spider monkey. The length of its body is 58.31 cm. The Length of its tail is 78.96 cm. To the nearest tenth of a centimeter, estimate the total length of the monkey’s body and tail. 58.31 + 78.96 58.3 + 79.0 • Round to nearest tenth 137.3 cm • Add

  6. Estimating a Product • A rectangular kitchen is 8.5 ft long and 5.75 ft wide. Use rounding to estimate the area of the kitchen in square feet. 8.5 9 5.75 6 • Round each factor to the nearest whole number 9 * 6 = 54 ft2 • Multiply

  7. Extra Practice Estimate. Round to the nearest whole number before you add or subtract 1) 10.13 + 1.46 2) 14.17 - 10.92 3) 11.53 + 7.23 4) 9.35 - 0.81 11 3 19 8

  8. Extra Practice Estimate. Round to the nearest whole number before you multiply. 1) 4.9 x 12.2 2) 6.07 x 3.29 3) 7.65 x 5.33 4) 25.123 x 4.79 60 18 40 125

  9. Estimating by Front-End Estimation • Useful for finding sums or differences. • Two Steps: 1) Add (Subtract) the front numbers 2) Estimate the sum of the lesser numbers and adjust the estimate

  10. Estimating by Front-End Estimation • Suppose you went food shopping with your parents this weekend and bought Lucky Charms for $3.21, a frozen pizza for $4.79, Pepsi for $1.99, and a pack of gum for $1.15. Estimate the total cost of your purchases. Step 1: Add the front-end digits $3.21 $4.79 $1.99 +$1.15 $9 Step 2: Estimate the total amount of cents to the nearest dollar. $3.21 $4.79 $1.99 +$1.15 $2 About $1 About $1 The total cost is about $11.

  11. Extra Practice • A group of runners run a relay race in which each runner decides how long they run for. Their distances were 3.9 miles, 2.1 miles, 1.7 miles, 1.2 miles, and 3.3 miles. Estimate the total distance of the race. Step 1: Add the front-end digits 3.9 2.1 1.7 1.2 + 3.3 10 Step 2: Estimate the total amount of tenths of a mile to the nearest mile. 3.9 2.1 1.7 1.2 + 3.3 2 About 1 About 1 The total distance is about 12 miles.

  12. Extra Practice Use Front-End Estimation to estimate each sum. 1) 5.43 + 2.67 2) 8.09 + 11.24 3) 7.18 + 5.89 4) 3.62 + 2.31 8 19 13 6

  13. What is a compatible number? • Numbers that are easy to compute mentally. You can use compatible numbers to estimate. • Change the numbers of the problem to make the calculation easier. • Useful for finding quotients.

  14. Using Compatible Numbers • It took 75.75 pounds of shredded cheese to make the world’s largest burrito. Use compatible numbers to estimate how many 10 pound boxes of shredded cheese the cooks needed. 75.75 10 Set up the Quotient 80 10 Choose compatible numbers such as 10 and 80.

  15. Extra Practice Use compatible numbers to estimate each quotient. 1) 76.5 ÷ 8.8 2) 19.45 ÷ 4.92 3) 103.6 ÷ 9.72 4) 32.2 ÷ 7.56 9 4 10 4

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