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4.4 Estimating with Decimals

4.4 Estimating with Decimals. Homework. Mental Math. Give a whole-number estimate for these decimal addition problems. Show which whole numbers you used: 3.8 + 9.9 = EXAMPLE: 4 + 10 = 14 2.7 + 8.1 = 10.5 – 6.6 = 8.8 + 8.9 = 23.7 – 8.8 = 25.5 + 11.9 = 26.2 – 10.8 =. Math Message.

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4.4 Estimating with Decimals

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  1. 4.4 Estimating with Decimals

  2. Homework

  3. Mental Math Give a whole-number estimate for these decimal addition problems. Show which whole numbers you used: 3.8 + 9.9 = EXAMPLE: 4 + 10 = 14 2.7 + 8.1 = 10.5 – 6.6 = 8.8 + 8.9 = 23.7 – 8.8 = 25.5 + 11.9 = 26.2 – 10.8 =

  4. Math Message Turn to a tablemate and describe two examples in which decimals are used in real-life situations. Measurement: Money: Other:

  5. Why are decimals useful? SRB Page 26:

  6. Trip Meters and Speedometers What information would we get if it just showed whole numbers of miles traveled? Decimals make it possible to have a more precise measurement of distance traveled. Below the speedometer shows tenths of a mile. Have you traveled closer to 45 miles or 46?

  7. How do I round decimals? • Rounding decimals are very similar to rounding whole numbers-the only difference is there is a decimal point! • Look at the digit to the right of the place you are rounding • Think about this poem If it is 4 or less just ignore, If it is 5 or more add one more!

  8. Rounding to the nearest tenth • Round to the nearest tenth 5.263 • The number to the right of the 2 is a six. • Six is greater than five, so I need to add one more the 2. The 2 becomes a 3 and everything after becomes a 0 • 5.263 rounded to the nearest tenth become 5.300 or 5.3

  9. Rounding to the Nearest Hundredth • Round to the nearest hundredth • Remember 4 or less just ignore, 5 or more add one more! • 3.653 The number to the right of the 5 is an 3. 3 is less than 4, so we just ignore-meaning the five in the hundredths place stays the same. • The 5 stays the same and all the other numbers after it become zeros The correct answer is: 3.650 or 3.65

  10. More Practice • 2.34 • 46.675 • 232.23 • 96.782 • 0.45 • 12.322

  11. Estimating Decimal Sums MJ p 85 Must answer the questions by using ESTIMATION, not by calculating exact answers.

  12. Partnership Work – MJ p. 83

  13. MJ 85

  14. Wrapping it UP! • In your math notebook, solve the following problems using estimation. 3.67 + 0.7 5.23 - 1.1 Write one new fact you learned about estimating decimals.

  15. Homework – Study Link 4.4

  16. Math Box 4.4

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