The installation progress screen shows package sizes in 'MBytes' and the accumulated sizes in 'M'. Because MByte has a lot of meanings (1000*1000, 1000*1024, 1024*1024) in the computer slang I suggest to use the standardized 'MiB' (Mega-Binary-Byte) notation (see hysics.nist.gov/cuu/Units/binary.html also)
Most users are familiar with the abbreviation 'MB', and not the one the NIST has standardized. I think it would be more confusing to change. Thank you for the suggestion.