The International System of Units
is called "SI"
and is the Metric Measurement
used in America.


SYMBOLS
IDENTIFY Prefix and
Base Unit or Derived Unit
or Unit of Measure
TOGETHER

   Symbols identify prefix and base or derived unit OR everyday unit of measure together. Simply place the prefix in front of the base or derived unit like mm (millimeter),
cm (centimeter), km (kilometer) or mg (milligram),
kg (kilogram) and mL (milliliter). 
The size or quantity is indicated by the first letter or
prefix symbol and the second letter or symbol
identifies the base or derived unit.

We easily identify the prefix centi when we think of 100 cents in the Unit  dollar. We could even refer to it as a "centidollar" and you come pretty close to doing that anyway by calling it 1 cent. There are exactly 100 cents in a dollar just like 100 cm (centimeters) in a meter. Got it? It just gets easier.

    Please Note: Where symbols are used convention has it that they are always lower case letters except where the Base Unit is named after a person like Celsius (°C), Pascal (P) or Newton (N).
 Then the symbol is noted by a CAPITAL LETTER.
So what's with a capital letter "L" for liter?
    Is that a capital "L" for the unit of measure named
after a person?
No....
    You see, when decimal dimensions were described long before the typewriter you would have to write the script.
    But as technology came along it became apparent that typewriters were not equipped with the script so attempts were made to use the lower case "l" (el).
   Then it became further confusing to write "1l" (lower case "el") as the "1" and "l" (el) looked too similar
as did the capital "I" (eye).
   So the capital "L" was chosen as the symbol for
the derived base unit "liter".

Use prefixes in front of the base or derived unit or unit of measure OR everyday unit of measure to make the Quantity, Size or Value
smaller by
1 one hundredth (0.01)
even smaller by
1 one thousandth (0.001)
OR bigger by
1000 times as much