Units of Measure
Prefix Symbol
Decimal
Value  Base 10 Base 2 (approx.)
yotta Y
1,000,000,000,000,000,000,000,000
.0 1024 280
zeta Z
1,000,000,000,000,000,000,000
.0 1021 270
exa E
1,000,000,000,000,000,000
.0 1018 260
peta P 1,000,000,000,000,000 .0 1015 250
tera T
1,000,000,000,000
.0 1012 240
giga G
1,000,000,000
.0 109 230
mega M
1,000,000
.0 106 220
kilo k
1,000
.0 103 210
hecto h
100
.0 102 26.64
deka da
10
.0 101 23.32
unit
1
.0 100 20
deci d
0
.1 10-1 2-3.32
centi c
0
.01 10-2 2-6.64
milli m
0
.001 10-3 2-10
micro µ
0
.000001 10-6 2-20
nano n
0
.000000001 10-9 2-30
pico (=micromicro) p
0
.000000000001 10-12 2-40
femto f
0
.000000000000001 10-15 2-50
atto a
0
.000000000000000001 10-18 2-60
zepto z
0
.000000000000000000001 10-21 2-70
yocto y
0
.000000000000000000000001 10-24 2-80

 
Medium  Capacity Typical Speed  (average access time)
Floppy Diskette 1.44 MB 300 ms = 0.300000000 second
Hard Disk Drive 2,000,000 MB
= 2,000 GB
= 2 TB
9 ms = 0.009000000 second
RAM 
(main memory)
1024 MB
= 1 GB
10 ns = 0.000000010 second  (SDRAM) 
         = 30,000,000 times faster than floppy disk
TB = TeraByte = 240 bytes = 1 trillion bytes (approx.) 
GB = GigaByte = 230 bytes = 1 billion bytes (approx.) 
MB = MegaByte = 220 bytes = 1 million bytes (approx.) 
ms = millisecond = 10-3 second = 1 thousandth of a second 
ns = nanosecond = 10-9 second = 1 billionth of a second