can anyone explain to me why a 10 megabyte hard drive does not contain 10 million bytes?

Question

it's a bonus question that my instructor gave at the bottom of our homework page.

Answer 1

As has been (kind of) explained, 1 MiB = 1024 KiB, and 1KiB = 1024 bytes. The "why," however, needs to be addressed.

At the most basic level, everything a computer does is in binary (ones and zeros, on and off). Hence, when dealing with bytes, it was easier to approximate powers of bytes to the nearest power of 2 (as it's thinking in base-2, or binary, instead of base-10/decimal).

When someone refers to ten megabytes, they usually mean (10 x 2^20)=10,485,760 bytes, which is quite close to 10,000,000. The prefix mega, however, when referring to SI units, denotes one million. To differentiate, there is the measure of binary bytes (kibibytes instead of kilobytes, mebibytes instead of megabytes, etc). Kilobyte = KB = 1000 bytes, kibibyte (kilo binary byte) = KiB = 1024 bytes.

So, technically, if a 10 meGAbyte hard drive does not contain 10 million bytes, it's a faulty drive, although odds are they just call it megabyte to avoid confusion (the -bi- infix wasn't officially adopted until 2000, but the original usage had been around before that). Confused yet? lol

Answer 2

Because of this:

1 megabyte = 1024 kilobytes (or 2 in the power of 10)
1 kilobyte = 1024 bytes,

so 1 megabyte = 1048576 bytes (or 2 in the power of 20)

Answer 3

There is not 1 000 000 bytes to the Mega byte thats why.
There is something like 1 240 000 or similar. Google will find the correct answer. 1 000 000 bytes is simply shortened

Answer 4

The hard drive needs its own space to use to hold its own information. There is a small file you can't see that holds the HD's parameters.

Think of mailing a letter. You have an envelope. You stuff letters in it, but without an address on the envelope, the letter doesn't go anywhere.

How's that?