1. Joined
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    25 Jun '14 08:25
    33 = 4! + 4 + sqrt(4)/.4
    34 = 4! + 4 + 4 + sqrt(4)
    35 = 4! +44/4
    36 = 4! + (4*4 - 4)
  2. Joined
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    25 Jun '14 23:592 edits
    37 = 4! + (4!+sqrt(4))/sqrt(4)
    38 = 4! + 4*4 - sqrt(4)
    39 = (4*4-.4)/.4
    40 = 44 - sqrt(4) - sqrt(4)
    41 = (4*4+.4)/.4
    42 = 44 - 4 + sqrt(4)
    43 = 44 - 4/4
    44 = 44 - 4 + 4
    45 = 44 + 4/4
    46 = 44 + 4 - sqrt(4)
  3. santa cruz, ca.
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    26 Jun '14 00:111 edit
    41 was nice
    is there another solution for 41?
  4. Joined
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    26 Jun '14 07:001 edit
    Not that I found, did you have a different solution for 39? ( My sols for 41 and 39 are similar)
  5. santa cruz, ca.
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    26 Jun '14 14:24
    no
    good job
  6. Joined
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    26 Jun '14 20:351 edit
    47 = 4!+4! - 4/4
    48 = 4! + 4! + 4 - 4
    49 = 4! + 4! + 4/4
    50 = 4! + 4! + 4 - sqrt(4)

    half way there - I'll let someone else have a go now

    by the way, are we allowed log?

    4/(log(sqrt(sqrt(sqrt(sqrt(sqrt(sqrt(sqrt(sqrt(4)))))))))/log(4))-4! = 1000
  7. Standard memberAgerg
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    26 Jun '14 22:554 edits
    4!/.4 -4/.4... = 51 (where the ... after the last 4 denotes 4 with a bar on it - i.e. 4 recurring)
    44 + 4 + 4 = 52
    44 + 4/.4... = 53
    44 + 4/.4 = 54
    (4! - .4)/.4 - 4 = 55
    4! + 4! + 4 + 4 = 56
    (4! + .4)/.4 - 4 = 57
    (4^4 - 4!)/4 = 58
    4!/.4 - 4/4 = 59
    44 + 4 * 4 = 60
  8. santa cruz, ca.
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    26 Jun '14 23:33
    logs are permissible I would assume
    as long as it is a mathematical symbol, function, etc
    very impressive the solution for 1000
    I have no idea how to work that out
  9. Standard memberAgerg
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    26 Jun '14 23:51
    Originally posted by lemondrop
    logs are permissible I would assume
    as long as it is a mathematical symbol, function, etc
    very impressive the solution for 1000
    I have no idea how to work that out
    Using the fact that log(x^n) = n log x we have that (I think there is one too many square roots)

    4/(log(sqrt(sqrt(sqrt(sqrt(sqrt(sqrt(sqrt(4)))))))))/log(4))-4! = 1000

    can be written 4 / log(4^(1/256))/log(4) - 4! = 256*4 / (log(4) / log(4)) - 4! = 1024 - 24 = 1000
  10. Standard memberAgerg
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    27 Jun '14 00:221 edit
    Well if we're allowed logs then (as per the wikipedia article for this puzzle) we have
    -sqrt(4)log(log(sqrt( ... n times ... (sqrt(4) ... ))/log(4))/log(4)
    = -2 log(2^(-n)log(4)/log(4))/log(4)
    = 2n log(2)/log(4) = 2n * .5 = n 🙂

    and so

    -sqrt(4)(log(log(sqrt(4))/log(4)))/log(4) = 1
    -sqrt(4)(log(log(sqrt(sqrt(4)))/log(4)))/log(4) = 2
    -sqrt(4)(log(log(sqrt(sqrt(sqrt(4))))/log(4)))/log(4) = 3
    .
    .
    .
    .
  11. santa cruz, ca.
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    27 Jun '14 04:312 edits
    The puzzle has been solved, I think
  12. Joined
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    27 Jun '14 07:445 edits
    Yes, we can even make every integer with just 3 fours (or, with a few small modifications, 3 of almost anything, except -1, 0 and 1):

    -(log(log(sqrt(4))/log(4))/log(sqrt(4)) =1
    -(log(log(sqrt(sqrt(4)))/log(4))/log(sqrt(4)) = 2
    -(log(log(sqrt(sqrt(sqrt(4))))/log(4))/log(sqrt(4)) = 3

    and so on
    The bit in bold changes, it has n nested square roots, where n is the integer required.

    It works because:
    sqrt(x) = x^(2^-1)
    sqrt(sqrt(x)) = x^(2^-2)
    sqrt(sqrt(sqrt(x))) = x^(2^-3)

    the maths surrounding the nested sqrts is needed to extract the bold number inside the power of x.

    the technique doesn't work for 1 or 0 because sqrt(1) = 1 and sqrt(0) = 0, so the nesting of the sqrts has no effect at all.
  13. Joined
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    28 Jun '14 09:54
    Can anyone answer the following bonus question:

    How many zeros do you need, combined with any other common mathematical symbols and constants, but no other digits, to make any integer?
  14. Standard memberAgerg
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    28 Jun '14 17:16
    Originally posted by iamatiger
    Can anyone answer the following bonus question:

    How many zeros do you need, combined with any other common mathematical symbols and constants, but no other digits, to make any integer?
    Well 0 factorial gets you a 1, and if we require an integer greater than one to apply the technique you mentioned above, then noting that 0! + 0! gives you 2 then 3 * 2 = 6. Which is the answer I'm going to shoot for.
  15. Subscribersonhouse
    Fast and Curious
    slatington, pa, usa
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    29 Jun '14 15:54
    Originally posted by Agerg
    Well 0 factorial gets you a 1, and if we require an integer greater than one to apply the technique you mentioned above, then noting that 0! + 0! gives you 2 then 3 * 2 = 6. Which is the answer I'm going to shoot for.
    How does 0! = 1? I thought factorial for zero would be zero, zero times one should be zero and one times zero should be zero.
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