Confused by a pattern

I have got to a part of the pattern where i need to make the button holes but i cant work out how they have made the stitches add up. Is it me or a typo? I have 43 stitches. The pattern reads:
Rib 4, cast off 2sts (rib 8, cast off 2sts) 3 times, rib 3.

I cant work out how this adds to 43 stitches, can anyone else?

Any suggestions?

The rib 4 or rib 8 means to work that many sts in ribbing. It takes working 3 sts to cast off 2 and I think they’re including the leftover st after the cast off. So rib 4, BO 2 takes 7 sts to do, (rib 8 cast off 2) 3 times takes 11 sts times 3; that will take you up to 40 and there’s the last 3 left.

Fabulous thank you very much