Finished files are the result of years of scientific study combined with the experience of years. How many F's are in the previous sentence?

Common Wrong Answers
“Two”
The guess 'two' may come from counting the first 'F' in 'Finished' and the second 'F' in 'files', missing the 'of's entirely.
“Four”
Many people might count the 'F's in 'Finished', 'files', and mistakenly include 'of' twice, leading them to overcount.
“Five”
The guess of 'five' often comes from an incorrect inclusion of extra 'F's, as the brain might misinterpret the 'of's while scanning the sentence.
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