How do Prestige class levels stack with base class levels?

Question

About to prestige my monk in the Psionic Fist class. The only part that I am confused on is with how the "Monk Abilities" class feature stacks with my base Monk class.

To my understanding it says that unarmed damage, bonuses to Armor Class and unarmored speed stack. I just don't know how to stack unarmed damage. But iffy about the other two. Ex. A Monk 6/Psionic Fist 3 would have 30 ft. Speed Bonus? Ex. A Monk 6/Psionic Fist 5 would get a +2 AC Bonus altogether?

But I have no idea how to stack Unarmed Damage. Then my final question would is, does anything else stack for going into Psionic Fist?

Answer 1

When levels in a prestige class stack with levels in a base class for purpose of determining the effects of a given class feature, calculate the benefit of the class feature as if the character had a number of levels in the base class equal to the character's number of levels in the base class plus the number of levels it has in the prestige class.

The only thing you're missing is that a Monk's Unarmed Damage depends on the character's Monk level. See the third column from the right on the Monk class table. A Monk 6/PF 3 would count as a 9th level Monk, giving it an unarmed damage die of 1d10 (and yes, have +30' speed bonus and an AC bonus of +1).

Any other class that progresses (stacks for calculating the benefits of) the given class features would add to the total effective Monk level.