Optical Illusion: Find S among the numbers in 4 seconds!

A grid of numbers is shown to readers in the image shared above. But there is one exclusion.  

Among the numbers is a letter that is concealing. Readers are challenged to find the letter S buried amid the numerals in under four seconds.  

Will you have enough time to identify it? Now is the beginning of your time! This is a short assessment to gauge your ability to observe.  

With the best eyes, one can identify S more quickly than others.  Examine the picture thoroughly. Did you manage to locate S? There's not much time left.  

Put an end to searching. I'd like to congratulate the readers who completed the challenge in time. Yours is the sharpest eyesight of all.  

Some of you may be asking where this challenge's solution is, am I right? View the response given above.  

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Optical Illusion: Find the dragon in the castle in 9 seconds!