Levelling Up - AD&D Rules clarification

[Hayashi]

In BG2 one had the option of obtaining max hps when levelling up a character. Unfortunately BG does not have this feature.

How do I calculate how what is the max hps my character/NPC should receive when levelling up, particularly dual & multi classed characters?

My CG Ranger has a CON of 17 and receives a +3 bonus to hps iirc. Coupled with a d10 roll for fighters, the min hp he should receive when levelling up should be 4 and the max 13 (on a die roll of 10) right?

How does the calculation work for multiclassed characters eg Jaheira who's a fighter/druid. She levelled up recently in both classes (the exp points to go to level 2 were the same - 2000 or so).

Any hints/help? Thanks.

[The Ozzman]

When i played the game through with jaheira i could never get more than a 6, but she levels up so often that in the end i think she had near 90 HP or something. Same goes for Yeslick(fighter/cleric), who is in my party now.

but all the tables should be included in the book that came with the game, start looking around page 135-140 they are all in there.

[Chris77Se]

If you have a multiclass char, you receive only 1/2 of the HD and the con-bonus. For Jah, this means, if she reaches a new fighter level, she will get 1d10/2 + 1.5 hp. When she levels up as a druid, she will get 1d8/2 + 1.5.hp. IIRC, fractions are rounded down, and you will always get at least one hp.