Interactive Voting - Estimation and Rounding

Estimation &Rounding Up

Front End&

Rounding

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Type your name and send:

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Estimation

The next few slides

will help you

test your

estimation skills.

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Can I buy three for $100?

45

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Can I buy three for $100?

$23

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Can I buy 5 for £50?

The basketball would have to cost ______ or less for me to purchase five of them for £50.

Answer in pounds.Next Page

Can I buy three for $20?

$4.95

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Roundingto the highest

Place Value

Round each number to its highest

possible place value. Some

numbers will be rounded to ten-

thousands, thousands, hundreds,

or tens.Next Page

375+ 26 + 1,427 + 216

375 Hundreds

26 Tens

1,427 Thousands

216 Hundreds

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Round to the highest place.

375 Hundreds 400

26 Tens 30

1,427 Thousands 1,000

216 Hundreds 200

Next PageWrite on board

After you round, add the numbers!

400

  30

1000

+ 200

1630

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8857

  4758

7045

+ 2110

8857

  4758

7045

+ 2110

9000

5000

7000

+ 2000

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A. Between 11,000 and 15,000

B. Between 16,000 and 20,000

C. Between 20,000 and 25,000

D. Between 28,000 and 33,000

9000

  5000

7000

+2000

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247

6542

489

+ 92

247

6542

489

+ 92

200

7000

500

+ 90

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200

7000

500

+ 90

A. A little less than 7,000

B. A little less than 8,000

C. A little more than 8,000

D. A little more than 10,000

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5028

6732

1285

+ 835

5000

7000

1000

+ 800

5028

6732

1285

+ 835

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Front End Estimation

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FRONT ENDThe name of this strategy gives you a clue

about how it is used.

The word FRONT should remind you that you are only concerned with the front portion of the number.

Many people think this strategy is easier than rounding to the highest place value.

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4,32 0

74 0

2,39 0

+ 2 0

4,329

748

2,398

+ 28

Draw a line through your list of numbers so that you have at least one digit from each addend in front of (before) the line.

Change all

numbers

after the line

to zeros.

All numbers

before the

line stay the

same.

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375+ 26 + 1,427 + 216

375 37 026 2 0

1,427 1,42 0216 21 0

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8857

  4758

7045

+ 2110

8857

  4758

7045

+ 2110

8000

4000

7000

+ 2000

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8857

  4758

7045

+ 2110

8857

  4758

7045

+ 2110

8000

4000

7000

+ 2000

Draw the line after the first number

In each addend.Next Page

• Between 11,000 and 15,000

• Between 16,000 and 20,000

• Between 20,000 and 25,000

• Between 28,000 and 33,000

8000

  4000

7000

+2000

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247

6542

489

+ 92

247

6542

489

+ 92

240

6540

480

+ 90

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Estimate to find the best answer.

240

6540

480

+ 90

• A little more than 7,000

• A little more than 8,000

• A little less than 9,000

• A little less than 10,0007350

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5028

6732

1285

+ 835

5000

6700

1200

+ 800

5028

6732

1285

+ 835

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Estimate and choose the most reasonable answer.

A. Between 11,000 and 15,000

B. Between 16,000 and 20,000

C. Between 20,000 and 25,000

D. Between 28,000 and 33,000

5000

6700

1200

+ 800

13700 Next Page

3,876

5,814

3,176

+ 7,895

4,000

6,000

3,000

+ 8,000

3,000

5,000

3,000

+ 7,000

A B

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9,876

8,514

6,092

+ 3,895

9,000

8,000

6,000

+ 3,000

10,000

9,000

6,000

+ 4,000

A B

End of show