To be fair, $7 billion is the number of tickets sold multiplied by the price of each ticket. 528 million is the number of Mario games sold, not counting price, though it obviously includes the games that came bundled with the Nintendo consoles which gives it an unfair advantage in some ways (virtually every NES sold came bundled with Super Mario Bros., thus why that game is still the best "selling" Mario title with 40 million or so units "sold"). When you consider that even the cheapest Mario games sell for at least $20 (I think I'm being generous to Potter here too), Mario makes Potter look like the boy who died. But, for a 100% fair comparison, one should compare the total franchise value (books, movies, games, merchandise, etc.), in that case Potter is leaps and bounds ahead of the famed Italian plumber (by roughly $10 billion in franchise value).