#6. Brain teaser: can you count the Fs in this sentence?


Quick! Count the num­ber of times that the let­ter F appears in the fol­low­ing sentence:


Fin­ished files are the result of years of sci­en­tif­ic study com­bined with the expe­ri­ence of years.”

How many did you find?


Solu­tionMost peo­ple say three. Why? We often don’t cor­rect­ly process the word “OF” for two rea­sons. First, the let­ter F usu­al­ly makes the “f” sound, like in “fox”. How­ev­er, in the word “of”, it makes a “v” sound. Sec­ond, you have prob­a­bly read the word “of” so many times in your life that you process it as one unit, over­look­ing the sec­ond letter/ sound.


Next brain teas­er in Sharp­Brains’ top 25 series:

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  1. Emily on August 20, 2008 at 1:08


  2. valesh on September 17, 2008 at 2:04

    there is actu­al­ly only one ‘F’
    rest five are’f’s
    see in the ques­tion he aasked ‘F’s but not ‘f’s

  3. Tasha on October 2, 2008 at 7:12

    six. the rea­son peo­ple were meant to count less is because our minds aren’t sup­posed to trans­late the F’s in the word OF

  4. Nicky on November 6, 2008 at 3:08

    I found 6 first try and actu­al­ly when I ini­tial­ly start­ed count­ing I glossed over the of but then stopped, went back and includ­ed the of’s in the count THEN read the expla­na­tion and had a chuck­le. Quite the lit­tle men­tal trick!

  5. NATACHA on November 6, 2008 at 4:08


  6. Joan on November 25, 2008 at 2:30

    six it is

  7. Erica on December 22, 2008 at 5:55


  8. Kiara on January 14, 2009 at 8:43

    i count­ed six

  9. Craig on January 17, 2009 at 12:44

    It is nev­er good to com­pli­cate a sim­ple thing. How about we change the intro to say,… “read aloud, the words you see below.”
    “Finished files are the result of years of sci­en­tif­ic study com­bined with the expe­ri­ence of years”… Then ask how many times the let­ter after the let­ter E in the eng­lish alpha­bet is used in what you just said?

  10. Rontre on January 25, 2009 at 3:07

    Hel­lo from the Bahamas.
    There are 6 f’s in the sen­tence. It’s basi­cal­ly here to say that the human brain does­n’t take in the word “of” as a word with f because it is said as “ov”.

  11. rach on February 23, 2009 at 11:38

    i found 4

  12. rach on February 23, 2009 at 11:39

    no wait i found 8

  13. ali on April 7, 2009 at 3:32

    6. There are only 6. Show me the others.

  14. Olivia on May 19, 2009 at 1:24

    At fist I count­ed 3, not even acknologing the F’s in the words like “of”. I then recount­ed it, and I count­ed 6.

  15. Dimwit on October 20, 2009 at 8:40

    I found 16

  16. kex on October 22, 2009 at 6:49

    Whats the answer to the rid­dle. tasha

  17. Dickface on November 2, 2009 at 4:31

    i cant count :(

  18. parv on November 12, 2009 at 1:47


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SHARPBRAINS es un think-tank y consultoría independiente proporcionando servicios para la neurociencia aplicada, salud, liderazgo e innovación.

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