# What's the largest number prefix we'll ever use in real life? **URL:** \ **Category:** Factual Questions\ **Created:** [February 13, 2011, 8:58pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242 "2011-02-13T20:58:35Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![Naxos](https://avatars.discourse-cdn.com/v4/letter/n/50afbb/32.png) [@Naxos](https://boards.straightdope.com/u/Naxos)\ **Post date:** [February 15, 2011, 6:54am UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/21 "2011-02-15T06:54:55Z")
> [@Lumpy](#): > > I.E., mega-, giga-, tera-, etc. I believe we’re currently up to peta (10[sup]15[/sup]) to describe the number of operations per second of a planned supercomputer. Current the largest prefix is yotta = 10[sup]24[/sup], comparable to Avogadro’s number or the number of individual atoms in a modest sample of matter. Will we ever need a bigger prefix to describe computing power? Yes. We are already indirectly using much larger numbers with the concept of [Cosmological Decades](http://en.wikipedia.org/wiki/Cosmological_decade), which is a time scale that maps out the future life of the universe. In a general sense, magnitude is not important in terms of causality. If things are small or big or bigger or immense is neutral in terms of causality of universal processes. The scale we can comprehend or describe those processes is unlimited and unimportant. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [February 15, 2011, 12:58pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/22 "2011-02-15T12:58:30Z")
> [@Naxos](#): > > In a general sense, magnitude is not important in terms of causality. If things are small or big or bigger or immense is neutral in terms of causality of universal processes. > > The scale we can comprehend or describe those processes is unlimited and unimportant. All true, but we still like to name things. As long as we continue to use fundamental units that seem reasonably sized for everyday life (e.g. kilogram, meter, second), we’re going to need a wide array of prefixes to create much larger/smaller units to gracefully deal with the extremes we encounter from time to time. Occasionally it’s necessary to abandon standard units altogether, although this only seems to be [commonly done in astronomy](http://en.wikipedia.org/wiki/Astronomical_system_of_units). At the other end of the scale, the only alternate unit I’m aware of is the [barn,](http://en.wikipedia.org/wiki/Barn_(unit)) which describes cross-sectional areas relevant to nuclear reactions. It’s 10[sup]-28[/sup] m[sup]2[/sup], a fraction of a square meter that doesn’t have a conveniently available prefix. To the OP’s question: > [@Lumpy](#): > > Current the largest prefix is yotta = 10[sup]24[/sup], comparable to Avogadro’s number or the number of individual atoms in a modest sample of matter. Will we ever need a bigger prefix to describe computing power? It’s hard to say yes with absolute certainty, but we’d be foolish to say no with _any_ certainty. There isn’t a correlation between Avogadro’s number and how fast a computer is, so there’s no reason to expect similar limitations in speed/nomenclature. ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [February 15, 2011, 1:15pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/23 "2011-02-15T13:15:10Z")
> [@Kevbo](#): > > On the other end, electrical engineers use pico (10\*\* -12) regularly and femto (10\*\* -15) occasionally. (picofarads capacitance and femptoamps leakage currents respectively would be the most common) > > ETA, pico was needed for decades before it came in to use. WW2 EEs would say “micromicro” Femtosecond lasers are reasonably common and have been around for decades. ---
**Author:** ![iamnotbatman](https://avatars.discourse-cdn.com/v4/letter/i/858c86/32.png) [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)\ **Post date:** [February 15, 2011, 1:36pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/24 "2011-02-15T13:36:18Z")
> [@Machine\_Elf](#): > > At the other end of the scale, the only alternate unit I’m aware of is the [barn,](http://en.wikipedia.org/wiki/Barn_(unit)) which describes cross-sectional areas relevant to nuclear reactions. It’s 10[sup]-28[/sup] m[sup]2[/sup], a fraction of a square meter that doesn’t have a conveniently available prefix. And in high energy physics we commonly use _femtobarn_ which stands for 10[sup]-43[/sup] m[sup]2[/sup]. Ideally we’d have chosen an even smaller unit than the Barn. As [Wikipedia](http://en.wikipedia.org/wiki/Barn_%28unit%29) says, some have tried to make up for this by coining the terms _outhouse_ (10[sup]-34[/sup] m[sup]2[/sup]) and _shed_ (10[sup]-52[/sup] m[sup]2[/sup]), but they haven’t stuck :(. ---
**Author:** ![GoodOmens](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@GoodOmens](https://boards.straightdope.com/u/GoodOmens)\ **Post date:** [February 15, 2011, 2:04pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/25 "2011-02-15T14:04:15Z")
I’m completely in favor of using “hella-” for 10^27 as long as 10^30 is “wickedpissah-” ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [February 15, 2011, 3:54pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/26 "2011-02-15T15:54:28Z")
> [@Naxos](#): > > Yes. > We are already indirectly using much larger numbers with the concept of [Cosmological Decades](http://en.wikipedia.org/wiki/Cosmological_decade), which is a time scale that maps out the future life of the universe. What is the significance of the crossbar in the upright part of the ‘D’ in the spelling of ‘Decade’ in that article? ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [February 15, 2011, 4:33pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/27 "2011-02-15T16:33:14Z")
> [@Machine\_Elf](#): > > At the other end of the scale, the only alternate unit I’m aware of is the [barn,](http://en.wikipedia.org/wiki/Barn_(unit)) … It’s 10[sup]-28[/sup] m[sup]2[/sup], a fraction of a square meter that doesn’t have a conveniently available prefix. How about the Ångström (10[sup]-10[/sup] m) as another example along those lines? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [February 15, 2011, 5:33pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/28 "2011-02-15T17:33:55Z")
> [@Bytegeist](#): > > How about the Ångström (10[sup]-10[/sup] m) as another example along those lines? The barn is of interest because it names a unit that’s far beyond the existing range of commonly used prefixes. Where the Ångström is concerned, there are smaller SI units that use standard prefixes, like the picometer (10[sup]-12[/sup] m) and the femtometer (10[sup]-15[/sup] m). ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [February 15, 2011, 5:55pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/29 "2011-02-15T17:55:52Z")
> [@Robot\_Arm](#): > > Yeah, I’m really hoping someday I can get a computer with a 1 harpobyte drive running a 4 grouchohertz processor. I just have to admit that I laughed WAY too hard at this comment. Damn, I’m a nerd (and a computer hardware engineer…) 😃 ---
**Author:** ![Naxos](https://avatars.discourse-cdn.com/v4/letter/n/50afbb/32.png) [@Naxos](https://boards.straightdope.com/u/Naxos)\ **Post date:** [February 15, 2011, 8:37pm UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/30 "2011-02-15T20:37:19Z")
> [@UncleRojelio](#): > > What is the significance of the crossbar in the upright part of the ‘D’ in the spelling of ‘Decade’ in that article? No idea. It’s probably the preference of the cosmologists that came up with the definition. This letter was used in old English and/or Scandinavian languages. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [February 16, 2011, 1:42am UTC](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242/31 "2011-02-16T01:42:44Z")
> [@Iggins](#): > > I just have to admit that I laughed WAY too hard at this comment. Damn, I’m a nerd (and a computer hardware engineer…) 😃 Thank you. I’ll be here all semifortnight; don’t forget to tip your waitron. [Previous page](https://boards.straightdope.com/t/whats-the-largest-number-prefix-well-ever-use-in-real-life/571242.md?page=1)