Each ruler should have hashes at the inch mark and every 1/16th of an inch. This would include half, quarter and eighths. So, basically, 9 and 3/4 would be rather close to what you want. 4/5 and 3/4 are only 1/20 apart. Unless you're building a motor or something, that's not a big deal.
Sorry can't help you, but LOL, I don't feel so lonely any more. I never could grasp rulers or tape measures. I was awful at the "new math", fractions, decimals, and the list goes on and on.