That's depend on what is being measured. Are you measuring storage capacity? Are you measuring a file? A 10MB hard drive would be considered tiny by today's standards. A 10MB text file would be considered huge.
To what are you referring?
There are 1024 megabites in 1 gigabite. 20 gigabites has 20,480 megabites.
how much time does it take to use 250 megabites when the computer is in use?
4.504 Mb
1024
5500
2980
None
4500
Yes, they are.
4gb = 4,096mb
1.306728 gb
5000 megabites