I have ripped several songs to the HD, saved it to a folder.

I would like to know the size of each song that is in that folder. When I rt-click, select Properties, it shows the following:

Size: 34.5MB (36,253,186 bytes)
Size on disk: (printed same as above)

Can someone explain which is the correct size and why the figure shown in parentheses is greater than the other.