Formulae for Piercing Arrow & Iron Arrow?

Wasn't sure whether or not to put this Maple Q&A or not, but whatever.
How does the damage formula scale up/down when Piercing/Iron Arrow travels through more than one target?

Iron Arrow:
D = 0.9 ^ (OrderHit - 1)
Cumulative damage = 10 * (1 - 0.9 ^ NumHits)

Pierce:
D = 1.2 ^ (OrderHit - 1)
Cumulative damage = 5 * (-1 + 1.2 ^ NumHits)

So Level 32 Pierce would do 1180% * 1.2^(6) on the seventh monster it hits?

So Level 32 Pierce would do 1180% * 1.2^(6) on the seventh monster it hits?

I'm supposing that's how it works.