LOL, "Nineteen and two thirds inches".
Even though in hindsight I should have thought about using the metric tapes for the drywall exercise, it would have broken the "don't mix measuring systems in a project" rule, at least for the overall project. Then again, it would have been limited to a single operation and therefore, it wouldn't have mattered or brought any real risk. In fact, it would have been less risky given the circumstances. But in the end, all worked out with all the holes in the correct places and tight enough to the boxes that I'm not going to have to slather a lot of mud to close anything up.
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The most expensive tool is the one you buy "cheaply" and often...