Say how are multi class HP figured? For example an elf fighter/thief/mage with say 18 constitution, which would be 14/8/6 HP per level (for a straight class), I'm sure they don't just add them together. Maybe they divide by three. If so that would be 4.6 fighter/2.6 thief/2 mage and after level 9 1 fighter/.6 thief/.3 mage
And how would they handle the fractions? I'm curious Any one know?

it looks like they divide the hit die first... then divide the(highest?)bonus by 3 and add them together..
seems like they round down.. but i haven't futzed with triple classed characters too much (very powerfull, but too slow to develop unless it's a one or two man party)