A good many years ago I got a letter from the Internal Revenue Service telling me that I had made a math error on my income tax return and that I owed more money. That seemed odd to me, since I was using commercial income tax software to do the return and usually those programs are pretty good at arithmetic.
After some research comparing my numbers to the IRS numbers, I found the problem. They had made a typographical error keying or scanning my return, putting a “0” where I had a “9”.
Do you know what happens if you make that mistake when typing a Hawaiian zip code? It comes out Connecticut.