Orders of Magnitude: Natural Exponential Numbers and Physical Properties

Power of 10

Physical Property

Name or Prefix

Symbol

10^-35

length in meters where spacetime becomes dominated by quantum effects, the
Planck length

10^-24

yocto–

y

10^-21

zepto–

z

10^-19

charge of one
electron

10^-18

atto–

a

10^-15

the radius in meters of one proton
(hydrogen nucleus)

femto–

f

10^-12

pico–

p

10^-10

radius in meters of a hydrogen atom

10^-9

number of seconds it takes light to
travel one foot

nano–

n

10^-8

period in seconds of an FM radio wave

10^-7

wavelength
in meters of germicidal Ultraviolet
radiation

10^-6

micro-

m

10^-3

milli–

m

10^-2

centi–

c

10^-1

fraction of stars
that can support life

deci–

d

10⁰

a) all is one

b) density of water in grams per milliliter

one

—

10¹

a) fingers on human hands

deka–

D

10²

a) human lifespan

b) number of stable elements in the
periodic table

hecto–

h

10³

speed of sound
in km/h

kilo-

k or K ^**

10⁵

number of hairs on a human scalp

10⁶

mega-

M

10⁷

number of seconds in a year

10⁸

a) number of people on earth (circa
500BC)

b)
number of meters light travels in one second

10⁹

a) number of people on the earth (circa
1800)

b) number of heartbeats in a lifetime
for most mammals

giga–

G

10¹⁰

number of people on the earth (circa
2050)

10¹²

a) number of cells in the human body

b) number of data bits on a
computer hard disk

tera–

T

10¹³

national debt of USA in
dollars (circa 2008)

10¹⁴

number of neural
connections in human brain

10¹⁵

surface area of the earth in square
meters

peta–

P

10¹⁶

speed of the fastest computer in FLOPS
(circa 2008)

10¹⁷

age of the universe in seconds

10¹⁸

volume of water in the earth’s oceans in
cubic meters

exa–

E

10¹⁹

number of possible positions of Rubik’s
cube

10²¹

volume of the earth in cubic meters

zetta–

Z

10²⁴

a) number of grains of sand in the Sahara desert

b) number of atoms in one
mole (the Avogadro constant)

yotta–

Y

10²⁸

mass of the earth in grams

10³³

mass of the solar system in grams

10⁵⁰

a) number of atoms in the earth

b) number of possible chess
board positions

10⁶⁶

number of atoms in our
Milky Way galaxy

10⁷⁸

volume of the universe in cubic meters

10⁸⁰

number of elementary particles in the
universe

10¹⁰⁰

googol

10¹²⁰

lower bound on the number
of possible chess games, also called the Shannon
number

10^googol

googolplex