Comment: In this case,

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In this case,

you would display the results on the giant screen at the front of the auditorium. Then there would be a layer of verification. I'd picture something like a seat chart, with each seat being green (yes), red (no), or black (abstain). Focusing in our your specific seat, you verify that your vote is correct. Looking at the whole chart would give you a fairly instant idea of what the total percentage vote is.

Again, this happens in college lecture halls regularly.