18. A small beastie is shown as viewed through the scanner objective lens in a microscope. The field of view of this scanner is 4000 micrometers.

The length of the beastie is about 1000 micrometers. You can calculate the length by estimating how many beasties would fit across the diameter of the field of view. If you estimate that 4 beasties would fit there, you would divide 4000 by 4.

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