IXL | Estimate differences using compatible numbers

Use compatible numbers to estimate

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First, pick the better pair of compatible numbers.

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Now, use your choice to estimate the difference.

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is about

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Learn with an example

question

Use compatible numbers to estimate

–

First, pick the better pair of compatible numbers.

–

Now, use your choice to estimate the difference.

–

is about

key idea

Compatible numbers are good for estimating differences. They are close to the numbers you are given, and they are easy to subtract in your head.

solution

You want to estimate

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So, find compatible numbers that are close to 68 and 52.

70 is close to 68.

50 is close to 52.

70 and 50 are compatible numbers. They are easy to subtract in your head.

So,

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is a good way to estimate the difference.

Now, subtract the compatible numbers.

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So,

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is about

20.

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isn't as good of a way to estimate

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60 is too far from 52.

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Teacher tools

Work it out

Not feeling ready yet? These can help:

D.2Estimate sums using compatible numbers

P.4Subtract a multiple of 10 from a two-digit number

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