# Arithmetic/Geometry » Computer memory

 Symbol Name Number of bytes KB kilobyte 10001 = 103 = 1000 MB megabyte 10002 = 106 = 1 000 000 GB gigabyte 10003 = 109 = 1 000 000 000 TB terabyte 10004 = 1012 = 1 000 000 000 000 PB petabyte 10005 = 1015 = 1 000 000 000 000 000 EB exabyte 10006 = 1018 = 1 000 000 000 000 000 000 ZB zettabyte 10007 = 1021 = 1 000 000 000 000 000 000 000 YB yottabyte 10008 = 1024 = 1 000 000 000 000 000 000 000 000 Symbol Name Number of bytes KiB kibibyte 10241 = 210 = 1024 MiB mebibyte 10242 = 220 = 1 048 576 GiB gibibyte 10243 = 230 = 1 073 741 824 TiB tebibyte 10244 = 240 = 1 099 511 627 776 PiB pebibyte 10245 = 250 = 1 125 899 906 842 624 EiB exbibyte 10246 = 260 = 1 152 921 504 606 846 976 ZiB zebibyte 10247 = 270 = 1 180 591 620 717 411 303 424 YiB yobibyte 10248 = 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?

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?