Skyscrapers very often have two sets of floor numbers because some floor numbers are skipped or some double-height mechanical floors are counted as two stories. The drawings will usually show both floor numbers: actual floor number (a useful value for structural and mechanical purposes) and advertised floor number (a useful value for interior fit out). This is true of residential and commercial buildings alike: One World Trade Center is advertised as having 102 stories, but it’s actually 94 stories.