SI Unit Prefix
|
Prefix |
Factor by which the root unit is Multiplied |
Letter Symbol |
|
|
Decimal System |
Binary System |
||
|
Yotta |
1 000 000 000 000 000 000 000 000 = 1024 |
280 |
Y |
|
Zetta |
1 000 000 000 000 000 000 000 = 1021 |
270 |
Z |
|
Exa |
1 000 000 000 000 000 000 = 1018 |
260 |
E |
|
Peta |
1 000 000 000 000 000 = 1015 |
250 |
P |
|
Tera |
1 000 000 000 000 = 1012 |
240 = 1,099,511,627,776 |
T |
|
Giga |
1 000 000 000 = 109 |
230 = 1,073,741,824 |
G |
|
Mega |
1 000 000 = 106 |
220 = 1,048,576 |
M |
|
Kilo |
1000 = 103 |
210 = 1024 |
K |
|
Hecto |
100 = 102 |
¡¡ |
H |
|
Deka |
10 = 101 |
¡¡ |
DA |
|
Base Unit |
1=10 0 |
20 = 1 |
|
|
deci |
0.1 = 10-1 |
d |
|
|
centi |
0.01 = 10-2 |
c |
|
|
milli |
0.001 = 10-3 |
2-10 =1 / 1024 |
m |
|
micro |
0.000 001 = 10-6 |
2-20 =1 / 1,048,576 |
µ |
|
nano |
0.000 000 001 = 10-9 |
2-30 =1 / 1,073,741,824 |
n |
|
pico |
0.000 000 000 001 = 10-12 |
2-40 =1 / 1,099,511,627,776 |
p |
|
femto |
0.000 000 000 000 001 =10-15 |
2-50 |
f |
|
atto |
0.000 000 000 000 000 001 = 10-18 |
2-60 |
a |
|
zepto |
0.000 000 000 000 000 000 001 = 10-21 |
2-70 |
z |
|
yocto |
0.000 000 000 000 000 000 000 001 = 10-24 |
2-80 |
y |
¡¡
SI Unit
IEEE adopted the International System of Units in 1965 proposed in France 1960 (Systeme International d¡¯Unites)
Quantity SI Base Unit Unit Symbol
length/distance meter m
mass kilogram kg
time second sec
electric current ampere A
¡¡
bit - short for binary digit. In binary system a bit can be either 0 or 1.
Byte - In order to represent numbers, letters, and special characters, bits are combined into groups of eight bits called bytes. Each byte typically represents one character - in many computers, one addressable storage location. The capacity of main memory is expressed in numbers of bytes.
There are four commonly used units of measurement to describe memory capacity:
One Kilobyte - abbreviated k, KB, or k-byte - is equivalent to approximately 1000 bytes.
(More precisely, 1KB = 1024 bytes = 210 bytes. The older IBM PCs had a top capacity of 640KB, or about 640,000 characters of data.
One Megabyte - MB or M-byte - represents about 1 million (106) bytes. Precisely 1 KB x 1 KB = 1024 x 1024 = 210 x 210 = 220 = 1048576 bytes.
One Gigabyte - GB or G-byte - represents about 1 billion (109) bytes. Precisely 1 KB x 1 KB x 1 KB = 1024 x 1024 x 1024 = 210 x 210 x 210 = 230 = 1073741824 bytes.
One Terabyte - TB or T-byte - represents 1 about trillion (1012) bytes. Precisely 1 KB x 1 KB x 1 KB x 1 KB = 1024 x 1024 x 1024 x 1024 = 210 x 210 x 210 x 210 = 240 = 1099511627776 bytes.