Estimating Sums & Differences

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# Estimating Sums & Differences - PowerPoint PPT Presentation

Estimating Sums &amp; 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

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Presentation Transcript

Warm-Up

Find the value of each expression.

• 4.7 + 5.08
• 10 – 3.58

VOCAB

• Rational Number:
• a fraction made from integers
• Sum:
• 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

• less than one
• round to 0, ½ or 1
• mixed numbers
• round to the nearest integer (whole #)
Let’s Try Some Rounding…
• 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 _________
Example 1a

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
Example 1b

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
Example 2a

Estimate the value of .

• Each fraction is less than 1 unit from zero so round to the

nearest .

Example 2b

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?
Communication Prompt

Describe a time when you used estimating in a situation

outside of math class.