I suspect that the author has regurgitated an impressive-sounding calculation that has been doing the rounds since the time when there were far fewer A380s flying. Journalism eh?
Looks like the author has decided to abandon the tricky maths.
Amended version now reads:
With over 153 flights conducted daily by A380s at 31 airports they serve around the world, the A380 world fleet carries more than a million passengers per month
http://sky4all.wordpress.com/