# MathBench>Measurement

## The metric system

How well do you know your metric vocab? Below are a list of prefixes used in the metric system, arranged in order of size. Can you fill in the blanks?

 trillions billions millions thousands ones thousandths millionths billionths trillionths tera mega (none) pico

## Metric Quiz

To make this interactive, turn on javascript!

You already know the metric system? That's great. Below is a short quiz - if you can answer all 8 questions correctly within 4 minutes, feel free to skip this page. If not, you might want to brush up a little.

NOTE: do NOT put commas in your numbers -- the program is not smart enough to understand them!

The brain of an elephant can weigh up to 7.5 kilograms.
What is this in grams? g

Homo sapiens have a brain volume of about 1350 mL.
How much is this in liters? L

A mouse brain weighs about 400 milligrams.
What is this in micrograms? micrograms

Ribosomes start at about 11 nm.
How many micrometers is this? microns

A mitochondrion averages 0.5 micrometers across.
How much is this in nanometers? nm

Commander Spock identifies a new strain of bacteria which averages 17.83 micrometers.
How many nanometers is this? nanometers

The nerve cell running the length of a giraffe's neck can measure up to 3100 millimeters.
How much is this in meters? m
in micrometers? microns

Answers: 7500, 1.35, 400000, 0.011, 500, 17830, 3.1, 3100000

## If you need to brush up...

The easiest way to convert metric measurements is to move the decimal place. Remember that metric vocab? It went like this:

tera - giga - mega - kilo - no prefix - milli - micro - nano - pico

Every time you move to the right on this list, the unit gets smaller (by 3 decimal places), so you need more of them to compensate (move the decimal place 3 to the right).

 If you turn on javascript, this becomes a rollover
For example, an ostrich egg can be up to 0.12 meters. What if you need to convert this to millimeters? Since millimeters are smaller than meters, you will need more of them to cover the egg. So, move the decimal 3 places to the right:

 If you turn on javascript, this becomes a rollover
To convert to a larger unit, you need to move the decimal place to the left. For example, a microtubule is 25 nm in diameter. To convert the microtubule length to micrometers, you need to move the decimal place 3 to the left (so that there will be fewer micrometers than nanometers). So,

 If you turn on javascript, this becomes a rollover
If you need to convert between two prefixes that are not next to each other (i.e., milli to nano), just add up all the decimal places (in this case, 6 decimal places to the right).

For example, a human egg is 0.1 millimeters in diameter. So, in nanometers, this is:

To summarize, remember that the SMALLER the unit, the MORE of them you need to make the same measurement, so move the decimal in the appropriate direction.

Now try the quiz again...