Estimating Division Using Compatible Numbers

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Estimating Division Using Compatible Numbers

• Multiplication Facts Are the Key!

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What are compatible numbers?

• Compatible numbers are numbers from a fact
  family, a multiplication/division fact.
• Examples
• 42 6 35 7
• 24 8 100 10
• 90 9 18 3

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How are compatible numbers used in estimation?

• Steps
• 1. Find the places in the dividend that the
  divisor first goes into.
• 2. Convert those numbers into the closest fact
  family (compatible numbers)
• change the rest of the dividend to zeros.
• if needed the divisor can also be changed
• 3. Divide the fact, and place the zeros as needed.

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1. Find the places in the dividend that the
divisor first goes into.
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1. Find the places in the dividend that the
divisor first goes into.
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2. Convert those numbers into compatible numbers,
(if needed the divisor can also be changed)
Think The closest fact family for 6 is 6 x 7
42, so convert 41 into 42.
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2. Convert those numbers into compatible numbers,
(if needed the divisor can also be changed)
Think The closest fact family for 6 is 6 x 7
42, so convert 41 into 42.
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2. Change the rest of the dividend to zeros.
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3. Divide the fact, and place the zeros as needed.
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3. Divide the fact, and place the zeros as needed.
700