Number Prefixes

Yottabytes Are a Lotta Bytes

By Stephen Beck

Now that kilo-, mega- and even gigabytes of computer memory look like small beer, and computer clock speeds even in nanoseconds begin to feel pokey, it1s time to learn the next set of exponential prefixes destined to enter the modern vocabulary. Brace yourself for the coming world of computers with yottabyte memories and zeptosecond clock speeds (and Government deficits measured in petabucks).

Really Big Numbers

PREFIX POWER
of 10
UNITS NUMBER
kilo- 3 thousands 1,000
mega- 6 millions 1,000,000
giga- 9 billions 1,000,000,000
tera- 12 trillions 1,000,000,000,000
peta- 15 quadrillions 1,000,000,000,000,000
exa- 18 quintillions 1,000,000,000,000,000,000
zetta- 21 sextillions 1,000,000,000,000,000,000,000
yotta- 24 septillions 1,000,000,000,000,000,000,000,000

How long would it take someone to download a one- yottabyte file using a 28.8 baud modem? 11 trillion years.extremely long download time - 1 yottabyte

Really Small Numbers

PREFIX POWER
of 10
UNITS NUMBER
milli- ­3 one thousandth .001
micro- ­6 one millionth .000001
nano- ­9 one billionth .000000001
pico- ­12 one trillionth .000000000001
femto- ­15 one quadrillionth .000000000000001
atto- ­18 one quintillionth .000000000000000001
zepto- ­21 one sextillionth .000000000000000000001
yocto- ­24 one septillionth .000000000000000000000001
Source: National Institute of Standards and Technology

Illustration: Randy Jones for The New York Times

Copyright 1996 The New York Times Company