Topic explanation

Standard explanation

An SI prefix is a name and symbol attached to an SI unit to represent a specific decimal multiple or submultiple of that unit.

Key points

• Define an SI prefix.
• Recognize the names, symbols, and powers of common prefixes.
• Distinguish between multiples and submultiples of SI units.
• Convert prefixed units into base or coherent SI units.
• Convert squared and cubed units correctly.
• Prefix symbols are case-sensitive.
• Prefix and unit symbols are written without a space.
• Only one prefix may be attached to a unit.

Labelled diagram