I've been putting a lot of thought into Super Secret Knitting Project #2. I spent hours charting and recharting, I did a gauge swatch, I did math. I wound my yarn into balls, and I cast on. On the fourth round, I noticed that I seemed to be off--by about 30 stitches. I counted the stitches on my chart, then I counted the stitches on my needles.
Lo and behold, I had far too many stitches on my needles. I was supposed to have 65. I had 98.
Before I cast on, I took 65, added one for a k2tog at the join, and got 66. I divided 66 by 3 (three needles)... and got 33.
The highly intelligent among you may realize that 3 times 33 is not 66. It's 99.