saw something interesting in my email that day...

Count every 'F' in the following text:

FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS...

This is not a trick question. Look and count carefully!!!!
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The answer is...
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6!! Look again. Cos our brain cant process the word 'of'. Amazing right? Tell me if you managed to get it right.