The SI system
The International System of Units uses seven base units from which many derived units are built.
Units carry meaning
A number such as 5 is incomplete as a physical measurement until its unit and quantity are known.
Prefixes scale by powers of ten
Milli-, kilo-, micro- and other prefixes make very large or small measurements easier to express.
Consistency prevents errors
Unit mistakes can turn correct arithmetic into a physically wrong answer.
Source trail: NIST: SI units
This page explains scientific concepts for general learning. It does not replace laboratory safety procedures, professional engineering guidance, or individualized medical advice.