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By on January 4, 2014, with 84 Comments

Are you guys and gals out there ready for yet another brain teaser optical illusion? I know you all absolutely love these types of optical illusions, which is why I’ve started to focus more on posting brain teasers up for all of you out there. This brain teaser is one of those ones that are definitely going to mess with your mind. I would suggest reading over the paragraph first of all and then counting up all the F’s that can be found in the paragraph. However, it’s completely up to you. Either way, you should only count the F’s you find one time and then post your results in the comment section below this post. Now, I present you with this letter counting optical illusion.

Letter Counting Optical Illusion

© Gianni A. Sarcone, www.archimedes-lab.org. All rights reserved.

So, now that you’ve read over the image above, how many F’s were you able to count in the text? You should leave your answer below in the comments section and let us know what you came up with. I bet we will see a bunch of different answers. If you liked this optical illusion, you should let us know by leaving a rating. Also, don’t forget to share this with your friends and see if you can stump them, as well.


84 Responses
  1. Betty Killbuck says:

    I counted six Fs.

  2. Dian says:

    I counted 8. My strategy was to read the paragraph backwards.

  3. Gabriel says:

    2 Fs?

  4. Roofiss says:

    I count 8 of them.

  5. Roofiss says:

    No, there are 10.

  6. john forester says:

    i’m guessing 10; some words are repeated.

  7. Michael Jones says:


  8. merrick says:

    I got nine.

  9. .mau. says:

    how should I count the two cases of “of of” of which the text is peppered?

  10. Rodrigo Lustosa says:

    i found 10 Fs!

  11. Howard Brazee says:

    I counted 10, and only after noticed that the illusion wasn’t really about the number of F’s, but in the fact that we didn’t notice repeated OF’s.

  12. Lawrence Grace says:

    There are “9″ F’s.

  13. Michael Johne says:



    there are seven 7 in the paragraph


    there are seven F in the paragraph


    there are nine F in the paragraph


    10 f’c

  18. Richard Landesman says:


  19. Carl Fuglein says:


  20. donis says:

    9 F’s

  21. clay lister says:

    there were 9

  22. ovidel says:

    Is not the point of counting the “f”-s but not seeing the repetition of “of” in the text.

  23. FX Jiwanto says:

    There are 10 f’s found.

  24. JohnE says:

    I count 10. I’m guessing some duplicate words were meant to throw us off. If I’m wrong then I’ll like it.

  25. Guy says:

    There are 8 f’s

  26. Blair says:

    Hint: there are two of’s in the third, and fourth sentence.

  27. dabandit says:

    I count 10 1st & every try
    including the two double “of”s

  28. Jim says:

    eight + Two repetition of the word “of”, which people are likely to miss because they are too busy counting.

  29. Jrd says:

    I believe there are 9

  30. Eugene Kurtzer says:

    I found 9.

  31. dp says:

    10 F’s
    … of scientific … of of … Professor … of of … of … find … spaghettification

  32. Jeff says:

    9. But I knew what to look for.

  33. Jason says:

    I counted 10

  34. Ramyak Rohan Mohanty says:

    I got 9 F’s…..

  35. thelma huss says:


  36. Peach says:

    There are 0 ‘F’ in the text (but 9 ‘f’)

  37. Linda Muse says:

    I counted 9.

  38. FJL says:

    ‘f’ … total 9

  39. -zZz- says:

    There 10 f. But two of them are due to repeated “of”…

  40. cimone62 says:

    I found 8

  41. James Howde says:


    And re-reading it I missed the one in “University of Ushuaia”

  42. ojo says:

    You requested Capital-”F”. The answer is none.
    f is 10 times in the text.
    Greetz from Stuttgart

  43. Marcel says:

    I counted 10 f’s

  44. Belinda says:

    I counted 10

  45. Christine says:

    8 — with two “of of”s

  46. bdavidgiants10 says:


  47. Cameron says:

    The trick is that the human mind adimaticaly skips over the f’s in the word of.

  48. szmegma says:

    There is 10 “F”.

  49. Red says:

    10, if you got less recount the “of”s

  50. Tilley says:

    I had to count more than once

  51. Rabbit says:

    8. How are people getting 10? Re-read it, got 9… Still no 10…Nope, still 9…Hmm…

  52. Stuart says:

    Amazing… I went back and back, and could still only count 9. Went into photoshop and crossed out non-F’s and marked the F’s. Still only found 9.

    For some reason, like James, I didn’t see the “University of Ushuaia”. My brain seems to have chunked that as one unit without an ‘of’ in it!

    Great puzzle!

  53. Zero says:

    I didn’t count, but guys, do you see it? Word “of”
    mostly is seen two times in a row!

  54. Sarah says:

    i got 4. so confused.

  55. Sarah says:

    i counted again and got 6

  56. patty says:

    9 including the 2 extra ofs, now I’m going back to see if I missed one because some counted 10.

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