1. It’s all about the UNITS of Measure
SI UNITS Or
Metric Units
Here we are talking about PHYSICS - Energy, Machines and Motion + Physical Science.

2. System International (International System of Measurement)
That’s what SI stands for
It involves measurement based on the decimal system OR Powers of Tens
It is very easy to use that’s why we use it.
The other system of measurement is called British Engineering System or BE

3. British System Units Used only in the USA no place else!
These are units like inches, feet, pounds, ounces, miles, and degrees Fahrenheit for temperature.
It is very hard to convert say inches into feet yards- miles- etc.

4. SI UNITS You have units for: - Length ---- METER - Volume ---- Liter
- Mass Gram
- Temperature uses the Celsius Scale
Degrees Celsius or centigrade
ex. 28ºC

5. NEXT add special PREFIXES
You can add many prefixes to the basic units of the meter, liter and the gram
Using the basic six :
Kilo deci-
Hecto centi-
Deka milli-

6. For length ( meter ) Kilo- + Meter makes the kilometer km
Hecto-+ meter = the Hectometer hm
Deka- + meter = the Dekameter dam
deci- + meter = the decimeter dm
centi- + meter = the centimeter cm
milli meter = the millimeter mm

7. So you get it right? USE the Liter for volume yourself then.
Now also do the same for mass with grams.

8. POWER of TENS enters KILO- stands for 1000 x or 103
HECTO for x or 102
DEKA for x or 10 the one is understood
Deci for x or
Centi for x or 10-2
Milli for x or 10-3