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Estimating Sums & Differences

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Estimating Sums & Differences

Warm-Up

Find the value of each expression.

- 4.7 + 5.08
- 10 – 3.58

VOCAB

- Rational Number:
- a fraction made from integers

- Sum:
- ADD

- Difference:
- Subtract

- Rounding:
- Choose easy #’s close to hard #’s.

Estimating

Decimals

- less than one
- round to 0, 0.5 or 1

- more than one
- round to the nearest integer (whole #)
Fractions

- round to the nearest integer (whole #)
- less than one
- round to 0, ½ or 1

- mixed numbers
- round to the nearest integer (whole #)

- 0.2 rounds to ________
- 0.4 rounds to ________
- 0.7 rounds to ________
- 0.75 rounds to ________
- 1.6 rounds to ________
- ¼ rounds to _________
- 1/3 rounds to _________
- 3/5 rounds to _________
- 1 ¾ rounds to _________

Estimate the value of – 4.23 + 2.8.

- Both numbers are more than one and should be rounded to nearest integer.
- – 4.23 → – 4
- 2.8 → 3

- – 4 + 3 = –1
- – 4.23 + 2.8 ≈ –1

Estimate the value of 0.94 – (–0.43).

- Both numbers are less than one unit away from zero and should be rounded to the nearest 0.5.
- 0.94 → 1
- – 0.43 → – 0.5

- 1 – (–0.5) = 1 + 0.5 = 1.5
- 0.94 – (–0.43) ≈ 1.5

Estimate the value of .

- Each fraction is less than 1 unit from zero so round to the
nearest .

Estimate the value of .

- Each fraction is more than 1 unit from zero so round to the nearest integer.

Estimate the value of each expression.

- 3.21 + 6.3
- 0.13 – 0.925
- Matt bought pounds of apples, pounds of grapes and pounds of potatoes. How many pounds did he buy?

Describe a time when you used estimating in a situation

outside of math class.