## Computers, file size, units of measurement and storage devices

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During my teaching days ( I used to teach computer basics ) in 1999 / 2000, I made it a point to cover at least 1 lecture on units & measurements, file size and storage devices. The reason being many of my students were absolutely blank with regards to file size and the amount of data a floppy or a hard disk could store.

The basic unit used in computer data storage is called a bit (binary digit). Computers use these little bits, which are composed of ones and zeros, to do things and talk to other computers. All your files, for instance, are kept in the computer as binary files and translated into words and pictures by the software (which is also ones and zeros). This two number system, is called a “binary number system” since it has only two numbers in it. The decimal number system in contrast has ten unique digits, zero through nine.

Typical size of various computer files :

1. DOC files – 20 to 40 Kilobytes

2. IMAGE files – 20 to 200 kilobytes

3. MP3 files – 1000 to 4000 Kilobytes

The above sizes are theoretical and can exceed far more than mentioned.

A hard disk is measured in terms of Gigabytes and 3 1/2 inches floppy & Compact Disc in terms of Megabytes. These are 2 most commonly used storage devices apart from USB flash drives ( Storage capacity from 128 Megabytes to 10 Gigabytes ). If you are aware about the size of your file and the capacity of your storage device then it will become as much easier to know the amount of data that can be transferred to that device.

#### Computer – units of measurement

Computers – Bits & Bytes |
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bit | BIT | 0 or 1 |

byte | B | 8 bits |

kilobyte (decimal) | KB | 1000 bytes |

megabyte (decimal) | MB | 1000 kilobytes |

gigabyte (decimal) | GB | 1000 megabytes |

terabyte (decimal) | TB | 1000 gigabytes |

petabyte (decimal) | PB | 1000 terabytes |

exabyte (decimal) | EB | 1000 petabytes |

PLEASE NOTE : Real calculation should be based on the the following parameters ( 1 KB = 1024 bytes, 1 MB = 1024 KB and so on ).