Converting bytes to megabytes

Question

I\'ve seen three ways of doing conversion from bytes to megabytes:

1. megabytes=bytes/1000000
2. megabytes=bytes/1024/1024
3. megabytes=bytes/1024/100

Answer 1

BTW: Hard drive manufacturers don't count as authorities on this one!

Oh, yes they do (and the definition they assume from the S.I. is the correct one). On a related issue, see this post on CodingHorror.

Answer 2

Here is what the standard (SI) says:

http://physics.nist.gov/Pubs/SP330/sp330.pdf#page=34

Answer 3

Divide by 2 to the power of 20, (1024*1024) bytes = 1 megabyte

1024*1024 = 1,048,576   
2^20 = 1,048,576
1,048,576/1,048,576 = 1  

It is the same thing.