Check Your Math Using Alphabets

There are lots of simple tricks to help you check your math. There's a good chance that you already know about casting out nines to check arithmetic and using dimensional analysis to do a sanity check on your models. But there's one technique that I've found useful, but that I've never seen anybody else advocate (possibly because it can make your math look a little goofy). When doing math by hand, I've found that you can avoid lots of silly mistakes by using different alphabets for different types of values. (Warning: You may need a decent Unicode font installed to make sense of the rest of this post.)
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