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# Using Estimation Strategies - PowerPoint PPT Presentation

Round to the place of the underlined digit. 1. 3,528 2. 24,106 3. 54 4. 131,295 5. 449 6. 4,951 7. 229,999 8. 82,729 9. 998 10. Round 3,507 to the nearest ten, nearest hundred, and nearest thousand. Solutions 1. 2. round down; 3,500 round up; 24,110

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## PowerPoint Slideshow about 'Using Estimation Strategies' - erin-parsons

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1. 3,528 2. 24,106 3. 54

4. 131,295 5. 449 6. 4,951

7. 229,999 8. 82,729 9. 998

10. Round 3,507 to the nearest ten, nearest hundred, and

nearest thousand.

Solutions

1. 2.

round down; 3,500 round up; 24,110

3. 50 4. 130,000 5. 400 6. 5,000

7. 200,000 8. 83,000 9. 1,000 10. 3,510; 3,500; 4,000

Using Estimation Strategies

COURSE 2 LESSON 1-1

(For help, go to Skills Handbook p. 697.)

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There are three types of Estimation:

(that we are going to look at)

1. Estimate by rounding

2. Front-end estimation (useful for finding sums)

3. Compatible numbers (useful for division)

78.96 + 58.31 80 + 60 Round to the nearest whole number.

Estimate by Rounding

COURSE 2 LESSON 1-1

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 centimeter, estimate the total length of the monkey’s body and tail.

1. ADD/SUB: Decide which place is best to round to and then round all numbers to that place. (Usually the highest place in the smallest number)

2. Perform the given operation using the rounded numbers.

3. Give your answer with an approximately equal to () sign and units.

The total length is about 140 cm.

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8.75 9

18.5 20

20  9 = 180 Multiply.

Estimate by Rounding

COURSE 2 LESSON 1-1

A rectangular kitchen is 18.5 ft long and 8.75 ft wide. Use rounding to estimate the area of the kitchen in square feet.

When estimating with multiplication, round each factor to its highest place value.

You should only have to multiply a single digit times a single digit.

Remember, the zeros only hold the place value, so they can be put back when the multiplication is complete.

The area of the kitchen is about 180 ft2.

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• Homework

• Section 1-1 # 1-6

• Homework

• Section 1-1 # 7-12

• Estimate first, then do the actual multiplication to see how close your estimate was

Very useful for finding sums of several items. (for example when shopping or in line at McD’s)

2. Estimate the sum of the lesser numbers and adjust the sum appropriately.

\$2.87

\$6.33

\$4.11

\$3.95

So this trip to the store should cost you about \$17.

\$15.

+ 2

= 17

\$3.79

\$1.39

\$0.89

\$2 = \$6

\$3.79

\$1.39

+ \$0.89

\$4

Front-End Estimation

COURSE 2 LESSON 1-1

At a snack shop, you order a taco that costs \$3.79, a juice that costs \$.89, and a yogurt that costs \$1.39. Estimate the total cost of your order.

Step 1: Add the front-end digits.

Step 2: Estimate the total number of cents to the nearest dollar.

The total cost is about \$6.

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8.25

Set up the quotient.

1. Round the divisor.

2. Choose a number that

goes in evenly, (i.e. is compatible.)

___

7 Simplify.

Estimation by Compatible Numbers

COURSE 2 LESSON 1-1

Suppose you have saved \$58.80. About how many CDs can you buy if each costs \$8.25?

56

8

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COURSE 2 LESSON 1-1

Pages 7–9 Exercises

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COURSE 2 LESSON 1-1

Pages 7–9 Exercises

• (59.78)

• (120.33917)

• (900.9484)

• (19.9703)

• (162.7024)

• (40.7745)

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COURSE 2 LESSON 1-1

b. Answers may vary. Sample: 15 of the 198.7-lb boxes and

3 of the 287.2-lb boxes for a total of 18 boxes

27–32. Answers may vary. Samples are given.

27. about 43.3; estimate by rounding each number to the nearest whole number.

28. about 4,296; rounding makes it easier to get an estimate.

29. about 40; 360 is compatible with 9.

4  2 = 8

32. 4; use compatible numbers 8 ÷ 2

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COURSE 2 LESSON 1-1

37–39. Answers may vary. Samples are given.

South Pole Sta.: about 0 in.

44. Round one of the numbers,

then find a multiple of that number

that is near the other number.

Samples are given.

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53. A

54. H

55. D

56.[2] \$54 with reasonable justification

[1] correct answer, without error in either estimate or justification

57. 4; 40; 403; 4,004

58. 7,068, 7,618, 7,680, 7,681

49. The second choice; the first choice cost about \$33 per dozen. The second choice cost only about \$30 per dozen.

50. The first choice; the first choice is less than \$3 per pair while the second choice is more than \$3 per pair.

52. 899

Using Estimation Strategies

COURSE 2 LESSON 1-1

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COURSE 2 LESSON 1-1

59. two hundred forty-eight

and nine tenths

60. four hundred thirty-one

and eighty-five hundredths

61. four and twenty-eight hundredths

62. one hundred thirty and

three hundred ninety-six thousandths

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