The BIPM specifies twenty-four prefixes for the International System of Units (SI).
The first uses of prefixes in SI date back to the definition of kilogram after the French Revolution at the end … See more

Examples
• The mass of an electron is about 1 rg (rontogram).
• The mass of 1 litre of water is about 1 kg (kilogram).
• The mass of the Earth is about 6 Rg (ronnagrams). See more

Obsolete metric prefixes
Some of the prefixes formerly used in the metric system have fallen into disuse and were not adopted … See more

• Binary prefix – Symbol placed before units of digital information to indicate multiplication by a power of two
• CJK Compatibility – Unicode block (U+3300-33FF) containing various characters composed into ideographic squares, and … See more

The use of prefixes can be traced back to the introduction of the metric system in the 1790s, long before the 1960 introduction of the SI. The prefixes, including those introduced after 1960, are used with any metric unit, whether officially included in the SI or not (e.g., … See more

In written English, the symbol K is often used informally to indicate a multiple of thousand in many contexts. For example, one may talk of a … See more

• International Bureau of Weights and Measures (BIPM)
• SI prefixes at BIPM
• US NIST Definitions of the SI units: The twenty SI prefixes
• US NIST Definitions of the SI units: The binary prefixes See more