I totally understand the math thing. I am good at figures. But, I really did not geometry. I made that statement so many times that my dh (the geometry teacher) quotes me everytime I ask him a question and adds "if you only would have listened in class". I am so glad I don't ask him very often.
I too came up short a few quilts ago. Measured just the way quiltville says. I have no clue what happened. I just must not have been careful enough or just totally spaced out. I feel you pain, LOL!