Actually, its not quite that simple. oops, I see Shawn has already given more info on why ohms law is less simple to use for AC electricity like we all use. One of the tables further in that article should help though.
Although you are correct that you do not NEED to have the monitor(s) on the UPS, I generally prefer them on UPS JIC the systems do not shutdown automatically or in case you wish to interrupt the shutdown. If the monitor goes off with the power, you are helpless.
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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr. Seuss