A hard disk is divided into tracks which are further subdivided into:

sectors

Explanation:

hard disk contain tracks which are further divided into sectors, for storage purposes.

to change your username, you must:

1) make sure what the username you want to change to is allowed in this community

2) contact a administrator (for example, jaysl)

3) through pm, tell the admin what you want to change to

4) if the username is allowed, it will be changed in a matter of seconds (minutes at most)

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professionals can use many types of technology that can them. some examples are, computers (they research and can use for programs for data, they are also used for job applications, school work, and even to make new ideas), speedometers (can get data for unknown data), sometimes something as small as a pen (used for rough drafts, to insert data, and again job applications).