How does damage % per hit work?

One thing I've never been absolutely sure about:

Example: If a Hero gets 100% more damage from ACA and does 300% x 3 with IS, does this mean that the Hero will be doing 400% x 3?.

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Another example: If a Paladin hits 200% x 3 = 600% with Blast and a charge gives 20% more damage, does the Paladin benefit from charge 60% overall? (660% total)

If Blast hit 100% x 6 = 600% with Blast and a charge gives 20% more damage, does the Paladin benefit from charge 120% overall? (720% total)