Ah yes, very good. This makes clear sense. I was under the impression that some goofy IU conversion was needed in figuring this out. But it's apparent now that they're meaningless really. I never used IU's in lab so was unfamiliar with that unit.

__This is simple dimensional analysis:__
Your goal is to determine mcg/tick:

1. 30 ticks/0.3mL = 100ticks/1mL

2. Thus, 1mL/100 ticks

3. (1mL/100ticks) x (1,000mcg/mL). (remember, 1,000mcg/mg)

4. The mL's cancel out, leaving 1,000mcg/100ticks = 10mcg/tick

I'm simply reiterating what Bobas said.

FYI: If you're using 0.5mL (0.5cc) slinpins (as I am), the calculations result in the same 10mcg/tick as found above! The slinpins will have 50 ticks and will hold 0.5mL, so ticks/mL = 50ticks/1mL ==>(invert) ==> 1mL/50ticks.