Help me do the math...

So, I decided to knit a cute little frilly brimmed hat for the little girl with leukemia. I found a "simple" pattern for one, and cast on yesterday. But here's where I'm stuck:

Cast on 270 stitches. (I know it seems like a lot, but the brim is quite frilly)

K 2 rounds.

*K 1, cast off 1* repeat for 1 round. 85 stitches remaining.

Ok, so I start with 270, I K1, cast off 1 for the entire round.... how in the world does that leave me with 85 stitches?! I know that I'm terrible with math, but it's just not possible. I thought maybe it meant to do a total of 2 rounds of K1, cast off 1, but then I have too few stitches.

Anyone with a little more knitting experience or just plain intelligence want to help me out? Otherwise I'm just going to wing it and see what happens (which usually ends up a disaster!)