What is "zepto-"

pre. In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻²¹. Symbol: z

Zepto- (symbol z) is a unit prefix in the metric system denoting a factor of 10 or .

Adopted in 1991, it comes from the Latin , meaning "seven", since it is equal to 1000.

Examples of its use:

• The electric charge on one electron: 160.217657 zeptocoulombs (zC).
• One zepto mole (zmol) of substance contains 602 particles.
• The human insulin molecule is roughly 10 zeptograms.