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# Estimation of Whole Number Multiplication and Division

## Estimate products and quotients with rounding.

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Practice Estimation of Whole Number Multiplication and Division

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Figuring Fish

Credit: Phil Manker
Source: http://www.flickr.com/photos/philmanker/4712166195/
License: CC BY-NC 3.0

Can you imagine having to count fish? Marine biologists do it all the time. They have the task of figuring out how many different species of fish are living in a reef. How do they do this?

#### Amazing But True

Diving down beneath the surface, marine biologists count and track different species of fish. Based on these numbers, they can determine the biodiversity of a reef. Some species are few and others are abundant. If one species of fish is expected to be abundant, but isn’t, then measures can be taken to help support the reef.

Credit: Laura Guerin
Source: CK-12 Foundation
License: CC BY-NC 3.0

Imagine this. A reef has been divided into four sections by 50 meter tapes. You, the marine biologist, dive down and count 10 of a certain species of fish in one division of the reef. After recording your data, you multiply that number by four (the number of sections), and estimate that there are 40 of that species of fish. Over time, you can see if this number grows in health or decreases in danger. Determining a dwindling population ahead of time can help save it from extinction.

See for yourself: http://youtu.be/bLZ8QNksTdM

#### Explore More

Check out how to conduct your own fish census!

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