While raging you have 50 % reduction slash, dludgeon and pierce damage .  Aspect of the bear brings more mitigaton.  again 50 % so if slashed for say 12 points of damge,  Do 50 % go down for B or S or P damag so damage goes down to 6.  With the aspect of the bear does damage get  reduced by another 50% so 6 would get reduced from 6 to 3. Is that correct?

Resistance doesn't stack.  (Neither does vulnerability). 

Aspect of the bear does not give you more resistance in the way of greater reduction - only more resistance in the way of more types of damage which are resisted. It's not giving you resistance to bludgeoning, slashing, and piercing again, it is making your rage which normally includes resistance to those three damage types provide resistance to all damage types except for psychic, so there wouldn't be anything to "stack" even if resistances did "stack" in some way (which, just to be absolutely clear, they do not).

Everything Aaron said. 

If you want a page number: https://www.dndbeyond.com/compendium/rules/basic-rules/combat#DamageResistanceandVulnerability

As a note.  It's the OPPOSITE of the classic Order of Operations of MDAS in Math.

In D&D it's SADM.  Subtraction or Addition then Division or Multiplication.

question does the bear totem worrier barbarian get resistance to force damage.

Quote from robo_robo >>

question does the bear totem worrier barbarian get resistance to force damage.

 Yes

Does the bear totem warrior have resistance to magical weapons s?

Quote from Griff66 >>

Does the bear totem warrior have resistance to magical weapons s?

 All barbarians, regardless of subclass, have resistance to magical piercing, slashing, and bludgeoning damage while raging.

To clarify, damage is broken down in the following ways:

Magical and Nonmagical, and then the type.

So for example, you can deal Magical Slashing Damage, and Nonmagical Slashing Damage.

Barbarians have resistance to Bludgeoning, Piercing, and Slashing damage when raging. To them, whether or not the weapon is magical is irrelevant  - they halve the damage when raging if it's one of these 3 types.

Bear Totem Barbarians have resistance to everything but Psychic damage, and again, this is regardless of magic or not. They halve the damage from anything except psychic, when they are raging.

Magical/nonmagical is relevant for other things. Some creatures say "Resistant to nonmagical bludgeoning, piercing, or slashing damage", meaning that if you slash them with a non-magical greatsword, they halve the damage they take. If you stab them with a magical dagger, they take full damage, because the damage is not "nonmagical piercing", it is "magical piercing", and so they do not have resistance to it.

Hope that clarifies!

Is it psychic damage?

• Yes: Barb takes all the damage.
• No: Barb takes half damage.

How about Ability damage? I haven't found any posts about this yet but I just took 9 Intelligence damage :( 

Quote from TKort >>

How about Ability damage? I haven't found any posts about this yet but I just took 9 Intelligence damage :( 

 

(unsure if this was meant as a joke but I'm not going to deny you info for my uncertainty!)

"Ability Damage" is a very, very rare one, and it does not have any resistances or immunities - when it does come up, it is supposed to be scary. It is not actually "damage", so it is never covered by any form of resistance or immunity, but it is instead an Effect. Typically it is worded along the lines of...

"The target's Strength score is reduced by 1d4"

And then explains how and when, if at all, the score returns.

When making homebrew, it's important to make certain that these conditions are in there, as there is no part of a long or short rest, or any spell I know of, that restores ability scores which have been reduced.