601.3952191 O’Clock?

My sister sent me the following amusing clock, where each hour is supposed to be represented by a mathematical expression involving only the number 9:


Math Clock


Each expression except one evaluates correctly to the respective hour. Can you find the erroneous hour?


SPOILER ALERT!  I posted the answer to the puzzle in the comment section of this post here.


6 Responses to “601.3952191 O’Clock?”

  1. ANSWER:

    As expressed, what should be 5 o’clock actually evaluates out to be 601.3952191, because the factorial (!) is under the square-root.

    √(9!) – 9/9
    = √(362,880) – 1
    = 602.3952191 – 1
    = 601.3952191.

    Rather, the factorial should be outside of the square-root to yield the intended answer 5:

    (√9)! – 9/9
    = 3! – 1
    = 6 – 1
    = 5

  2. E. Clifton Davis Says:

    Sorry, I can’t do the symbols you experts do but why not the square root of 9 + 9+9/2 ???

  3. E. Clifton Davis Says:

    Whoops, I meant:

    the sq rt of 9+9+9/9

  4. Virtuoid, why did you give the answer!!!? I was about to enjoy working it out but the answer was right there and you robbed me !!! 🙂

    • Oops! Sorry about that Abs!

      You bring up a good point. If it had been an email, I would’ve added a dozen blank lines with the warning “Spoiler Alert Below!”

      But you gave me a great idea to “hide” the answer in the comments. I’ll do this now.


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