# yotta- [YAH tuh or maybe YOH tuh]

#### (Greek: from octo-, "eight"; a decimal prefix used in the international metric system for measurements)

**yotta**- [YAH tuh *or maybe* YOH tuh] (Greek: from **octo**-, "eight"; a decimal prefix used in the international metric system for measurements).

Adopted by the Conference General des Poids et Mesures [CGPM] in Paris at its 19th meeting in October, 1991. This prefix is used in the metric [decimal] system as septillion [U.S.] or quintillionfold [U.K.], 10^{24} [1 000 000 000 000 000 000 000 000]. The metric symbol for **yotta**- is **Y**. "The names **yocto** and **yotta** are derived from **octo**, suggesting the number eight [the eighth power of 10^{3}]; the letter 'y' is added to avoid the use of the letter 'o' as a symbol because it may be confused with the number zero." Bureau *International des Poids et Mesures,* 1990, document #10, pp. 44-45.

^{24}bits (Binary DigIT, a single digit number in base-2 [a zero or a one] and is the smallest unit of computer data).

^{24}power bytes: "The yottabyte is the largest unit of measurement for computer data."

2. Mass of earth equal to about 6 000 yottagram.

^{24}meters or 10

^{21}kilometers. One yottameter equals 32.408 megaparsecs (Mpc) or 105.7 million light years.

It is said that we probably do not need a longer distance unit term than the "yottameter", because the radius of the observable universe is not more than about 200 yottameters.

Related **"metric"** families:
**zetta**;
**exa**;
**peta**;
**tera**;
**giga**;
**mega**;
**kilo**;
**hecto**;
**deka**;
**deci**;
**centi**;
**milli**;
**micro**;
**nano**;
**pico**;
**femto**;
**atto**;
**zepto**;
**yocto**.