I want to knit a round baby blanket. I found this round dishcloth pattern that I like:

http://www.mielkesfarm.com/dishclth.htm

It says that the finished cloth would be 10-12" across. I was thinking that I would enlarge the pattern first by casting on three times the number of stitches (it calls for 15, so I’d cast on 45). The instructions say to knit each even row until one more stitch is left on the needle (Row 2, knit until just one stitch is left on the needle, then up to row 18, with 9 stitches left), then turn the work. On the last row (Row 20 in the original pattern), three stitches are bound off so there are 15 stitches left (original number of stitches that were originally cast on).

But, with 45 stitches, would I continue the rows until I reach a row where if I bound off 3 stitches, then 45 would be left? So, theoretically, with 45 stitches (three times the original pattern), would I be knitting 60 rows (three times the original number of rows) to make the wedges and finished blanket all proportional?

Thanks for any help!