Zetta-


Zetta is a decimal unit prefix in the metric system denoting a factor of 1021 or. The prefix was added as an SI prefix to the International System of Units in 1991 and has the symbol Z.
The names zepto and zetta are implying the Latin numeral septem, meaning "seven", with the letter 'z' substituting the letter 's' to avoid the duplicate use of that letter as a symbol. Therefore zetta was used to denote the seventh power of 1000.
A prefix of the same value, hepta, was informally introduced a few years before the promulgation of zetta, but never received official sanction and is obsolete now. It was formed from the Greek ἑπτά, also meaning "seven" and already in use as a numerical prefix in this sense. Zeta, although the 6th letter of the modern and classical Greek alphabet, denotes a value of seven when used as a numeral.
Examples: