1. The SI System

2. What is the SI System?
The SI System (or the International System of Units) is the modern form of the metric system derived from 7 base units and the convenience of using multiples and fractions of the number 10.
The SI System is the world’s most widely used system of measurement with the USA being the only industrialized nation that does not use it as its primary system of units for commercial activity (although, the SI System is widely used in scientific fields in the USA).

3. The 7 Base units of SI System
Unit Name
Unit Symbol
Quantity measured
meter m
length
kilogram kg
mass
second s
time
ampere A
electric current
kelvin K
temperature
mole
mol
amount of a substance
candela cd
luminous intensity

4. How to use the SI System’s “Base 10” system. Factors > 1
Name
deca-(unit)
hecto-(unit)
kilo-(unit)
mega-(unit)
giga-(unit)
tera-(unit)
Symbol da h k M G T
Factor
100
101
102
103
106
109
1012
For Example:
A car weighs 3000 grams. In this case, a better way to represent the car’s mass would be to use the SI unit kilogram that best corresponds with the value. Therefore, the car weighs 3 kilograms, which is equivalent to 3000 grams.

5. How to use the SI System’s “Base 10”. Factors < 1
Name
deci-(unit)
centi-(unit)
milli-(unit)
micro-(unit)
nano-(unit)
pico-(unit)
Symbol d c m n p
Factor
100
10-1
10-2
10-3
10-6
10-9
10-12
Example
A fly’s wings are 23/1,000,000 meters thick. In this case, a better way to represent the fly’s wing thickness would be to represent it in terms of micrometers. Therefore, the fly’s wings are 23 micrometers thick, which is equivalent to 23/1,000,000 meters.

6. Note:
There are more metric prefixes beyond those listed.

7. Metric System vs. English System of Units – Table of Conversions
Common Length
Conversions
Common
Mass
Conversions

8. English System
The English System of Units, or Imperial System, isn’t as ubiquitous as the metric system, but still used today, mostly in the building industry.
It isn’t as convenient as the metric system, and its conversions are more difficult to calculate.

9. History and Progression of English Values for Mass

10. As you can see, the metric system, or SI system, is much more convenient for conversions between values of various magnitudes.

11. The End