I was going through the PHB again recently and read something in the barbarian section that makes me think I've been calculating HP increases wrong when I level up.
I noticed it says:
Hit Points at Higher Levels: 1d12 (or 7) + Constitution modifier per barbarian level after 1st
Does that mean that, when rolling for HP, I roll 1d12 then add my CON mod multiplied by each level after level 1?
Meaning (At level 6, with +3 CON): HP increase = 1d12 + (3 x 5)