Arithmetic/Geometry » Computer memory

Symbol  NameNumber of bytes
KBkilobyte10001 = 103 = 1000
MBmegabyte  10002 = 106 = 1 000 000
GBgigabyte10003 = 109 = 1 000 000 000
TBterabyte10004 = 1012 = 1 000 000 000 000
PBpetabyte10005 = 1015 = 1 000 000 000 000 000
EBexabyte10006 = 1018 = 1 000 000 000 000 000 000
ZBzettabyte10007 = 1021 = 1 000 000 000 000 000 000 000
YByottabyte10008 = 1024 = 1 000 000 000 000 000 000 000 000
 
Symbol  NameNumber of bytes
KiBkibibyte10241 = 210 = 1024
MiBmebibyte  10242 = 220 = 1 048 576
GiBgibibyte10243 = 230 = 1 073 741 824
TiBtebibyte10244 = 240 = 1 099 511 627 776
PiBpebibyte10245 = 250 = 1 125 899 906 842 624
EiBexbibyte10246 = 260 = 1 152 921 504 606 846 976
ZiBzebibyte10247 = 270 = 1 180 591 620 717 411 303 424
YiByobibyte10248 = 280 = 1 208 925 819 614 629 174 706 176

With 1 byte = 8 bits.
In numbers and units: 1 B = 8 b

Note: The K for kilo would normally be written in lower case (official SI-prefix), however with computer memory it is mostly written in upper case.

Example 1

The smallest piece of information (a letter, number or punctuation mark) that can be stored in a computer is called a byte. A certain book has 400 pages and an average of 3000 characters (letter, number or punctuation mark) per page.
How many MB of storage capacity is needed for this book?

Answer:
400 × 3000 bytes = 1 200 000 bytes = 1.2 × 106 bytes = 1.2 MB

Example 2

A large supercomputer has a memory of 1.6 PB.
How many mobile phones with a memory of 2 GB have the same storage capacity?

Answer:
number of mobile phones = memory supercomputermemory mobile phone
1.6 × 10152 × 109 = 0.8 × 106 = 800 000

Example 3

The speed of a certain internet connection is 15 Mb/s (megabit per second).
What is the speed in MiB/s?

Answer:
15 Mb/s = 15 × 1000 × 1000 : 8 = 1 875 000 B/s
1 875 000 B/s = 1 875 000 : 1024 : 1024 ≈ 1.788 MiB/s