There's something here I must not be explaining very well.
That week when everything was totally shut down -- the week of Monday, June 6, 1960 to Sunday, June 12, 1960 -- isn't counted in the total of the number of weeks a show ran.
Shows would shut down for even several weeks for various reasons, usually summer layoffs (which Gypsy did shortly after the strike, reopening in mid-August at the Imperial). Those weeks certainly aren't counted in the run of the show, nor is the week it was totally shut down due to the strike -- only the half-week is counted.
So not counting the strike week gave Gypsy a run of 89 weeks, not 90. So those missed 8 performances don't have to be subtracted from what the total the show would have run without a strike. That's why I only mentioned four performances missed due to the strike, which were the only four relevant to the discussion.
I guess I'm still not explaining this very well. :(