Talk:Numbers and symbols
Not all numbers are integers in MTG: occasionally, ½ appears either by itself or after an integer to add 0.5: "Little Girl", "Cheap Ass", "Smart Ass", "Bad Ass", "Dumb Ass", "Fat Ass", "Flaccify", "Necro-Impotence", "Vile Bile", "Wet Willie of the Damned", "Assquatch", "Sauté", "Fraction Jackson", "Stone-Cold Basilisk", "Supersize", "Letter Bomb", "Save Life", "Avatar of Me" and "Bosom Buddy".
Y is also used in the same manner as X. From the rules:
107.3i Some objects use the letter Y in addition to the letter X. Y follows the same rules as X.
There is even one card which uses the symbol Z in addition to X and Y: it's "The Ultimate Nightmare of Wizards of the Coast® Customer Service".
All of the cards I've named are official.