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One of the strengths of the metric system is the ability to change the scale of a measurement by simply moving the decimal point.  We show these scale changes by using metric prefixes.

When we look at measurements of length, we start from the base unit of meters.  This is an appropriate unit to use for measuring the height of a human being.  For example, I am about 1.80 m tall.  If we were measuring the length of my index finger, though, 0.09 m is a bit awkward.  Instead, we would most likely report this measurement as 9 centimeters.  Likewise, 1690 m is a lot of meters.  We would more likely report this as 1.69 kilometers.  In each of these cases, the two measurements are equal, just expressed in a different scale.

## The most common metric prefixes

milli-  1/1000 or 10-3

centi-  1/100 or 10-2

kilo- 1000 or 103

## Metric prefixes for very small numbers

With the computer age and nanotechnology, other prefixes have become more familiar over the years.

micro- 1/1,000,000 or 10-6

nano- 1/1,000,000,000 or 10-9

## Metric prefixes for very large numbers

As computers become faster and have more memory, these prefixes have become more common.

mega- 1,000,000 or 106
giga- 1,000,000,000 or 109
tera- 1,000,000,000,000 1012

### Pop Culture Reference

In the movie “Back to the Future”, the Delorean time machine required 1.21 gigawatts of electricity to operate.  Because this was such a large number, and most folks hadn’t experienced it yet, they mispronounced it as jiggawatts.  Very few people these days would brag about how their computer has 8 jiggabytes of memory.

Many modern computers have hard drives in the (TB) terabyte range.  This is quite a bit bigger than the 1.44 MB (megabyte) disks we used to use.