1-1 Using Estimation Strategies

1 / 15

# 1-1 Using Estimation Strategies - PowerPoint PPT Presentation

1-1 Using Estimation Strategies. Do Now: Round the following to the place of the underlined digit: 8 2 ,729 4 49 24,1 0 6 3, 5 28. Quick Tour of the Room. New Vocabulary. Compatible numbers: numbers that are easy to compute mentally ≈ Symbol that indicates estimation. Rounding.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about '1-1 Using Estimation Strategies' - hedy

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### 1-1 Using Estimation Strategies

Do Now: Round the following to the place of the underlined digit:

82,729

449

24,106

3,528

New Vocabulary
• Compatible numbers: numbers that are easy to compute mentally
• ≈ Symbol that indicates estimation
Rounding
• The span of an eagle ray’s fin is 3.27 m. The span of her baby’s fin is 0.88m. Estimate the difference between the spans. Round to the nearest whole number before you find the difference.
• 3.27−0.88≈3−1  Round to the nearest whole number

≈2 Subtract

Estimate.
• First round to the nearest whole number
• 1.75+0.92
• 14.34−7.8
• 4.90×6.25

2+1=3

14−8=6

5×6=30

Front End Estimation
• Add the “front-end” digits, ignoring the decimals.
• Estimate the decimals.
• Add the decimal estimate to the front-end sum.
Example

5.45

9.89

3.53

6.03

Front-end: 5 + 9 + 3 + 6 = 23

• Decimals:
• .89 is close to 1.
• .03 is close to 0.
• .45 + .53 is close to 1.
• 1 + 0 + 1 = 2

+

Put the front-end with the decimal: 23 + 2 = 25.

Compatible numbers go together!
• Compatible
• 54 and 9
• 16 and 4
• 32 and 8
• 12 and 3
• 54 and 6
• 18 and 2
• Not compatible
• 17 and 2
• 35 and 9
• 15 and 4
• 27 and 8
• 24 and 5
• 15 and 6
ESTIMATING Using Compatible Numbers
• Overbidding

52 ÷ 6 overbid 52 count up: 53 no

54 yes

32 ÷ 5 overbid 32 count up: 33 no

34 no

35 yes

7 ÷ 4 overbid 7 count up: 8 yes

Of course, you can use the multiples of the factor … multiplication facts.

ESTIMATING Using Compatible Numbers
• Underbidding

52 ÷ 6 underbid 52 count down: 51 no

50 no

49 no

48 yes

32 ÷ 5 underbid 32 count down: 31 no

30 yes

7 ÷ 4 underbid 7 count down: 6 no

5 no

4 yes

Of course, you can use the multiples of the factor … multiplication facts.

Compatible Numbers

Underbidding

Overbidding

20

17 ÷ 5 4

36

29 ÷ 9 4

48

42 ÷ 8 6

• 17 ÷ 5 3

15

• 29 ÷ 9 3

27

• 42 ÷ 8 5

40

TRY THESE

Use paper and pencil.

Check on next page.

• 73 ÷ 2
• 139 ÷ 2
• 236 ÷ 7
• 653 ÷ 9

Estimate

• Did you overbid?
• Did you underbid?
• Did you change numbers to zero?

80 40 140 70

73 ÷ 2 139 ÷ 2

70 35 120 60

280 40 720 80

236 ÷ 7 653 ÷ 9

210 30 630 70

Minute Time!