So..I hope I can explain this without going in circles...You know when you are doing a garment in the round, from the top down, and you separate to make armholes. At the bottom of the armhole you usually cast on a few stitches to each side and then re-join to knit the body in the round. The problem here is that there is a small hole at the first and last newly cast-on stitch. (At least for me).
This time, at each armhole, I cast on 2 more than the pattern said to, and worked my way on around. When I came to those newly cast-on stitches on the next row, I knit 2 tog with the with the last original stitch and the first cast on, and the last cast on and the first original stitch at the other end of the armhole.
Can anyone see what I'm saying here? It left me with an underarm without holes.