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 2017-05-29, 16:42 #1 R. Gerbicz     "Robert Gerbicz" Oct 2005 Hungary 1,531 Posts June 2017 There is a new Ibm puzzle: https://www.research.ibm.com/haifa/p.../June2017.html
 2017-05-29, 20:23 #2 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 227348 Posts Nice one! I think I have a "*" solution... (at least two) Last fiddled with by Batalov on 2017-05-29 at 20:32 Reason: there is more than one
 2017-06-05, 21:37 #3 R. Gerbicz     "Robert Gerbicz" Oct 2005 Hungary 27738 Posts There is an update: "Update (5/6): Division by zero is not allowed, but you can use non integers and unary minus (like the example above); and you get a '*' for every prime solution."
2017-06-05, 22:15   #4
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

22×2,423 Posts

Quote:
 Originally Posted by R. Gerbicz There is an update: "Update (5/6): Division by zero is not allowed, but you can use non integers and unary minus ..."
Instead of "non integers", he should have said "rationals". Or "fractions".
Or else we can do $$e^{i \pi}$$ or something like $$\sqrt 4$$.

Next month I am going to set up a webcrawler to watch the 'July2017.html' page
...so that I will not lose a couple hours to Robert ;-)

(This time I only learned of the problem launch from this thread.)

2017-06-06, 00:53   #5
uau

Jan 2017

112 Posts

Quote:
 Originally Posted by Batalov Instead of "non integers", he should have said "rationals". Or "fractions". Or else we can do $$e^{i \pi}$$ or something like $$\sqrt 4$$.
Not really. You can't insert arbitrary constants or operators into the expression (not integers or rationals either). The text only means that using the listed basic operators is allowed to create non-integer intermediate results (things like (1/3)*9 are allowed); allowing non-rational ones or not makes no difference as there are no operators which could create them.

2017-06-06, 01:38   #6
science_man_88

"Forget I exist"
Jul 2009
Dumbassville

26·131 Posts

Quote:
 Originally Posted by uau Not really. You can't insert arbitrary constants or operators into the expression (not integers or rationals either). The text only means that using the listed basic operators is allowed to create non-integer intermediate results (things like (1/3)*9 are allowed); allowing non-rational ones or not makes no difference as there are no operators which could create them.
then the term to use was rational. A non-integer includes the complement of the integers under the complex numbers etc.

 2017-06-06, 05:41 #7 LaurV Romulan Interpreter     "name field" Jun 2011 Thailand 232158 Posts grrr... another silly problem... the formulation is unclear, where and whenever you can/may/must place signs, and what's happening if you don't... "while other seven-digit numbers simply cannot be solved, such as 0314157" 0+3-1+41+57=100 skip.
2017-06-06, 05:46   #8
uau

Jan 2017

112 Posts

Quote:
 Originally Posted by science_man_88 then the term to use was rational. A non-integer includes the complement of the integers under the complex numbers etc.
Nope. There is no limit to integers or any other particular class of intermediate results. Complex numbers would be allowed if the list of operators included any that produced them. Them being allowed just doesn't matter because there's no way to produce them.

2017-06-06, 05:49   #9
uau

Jan 2017

112 Posts

Quote:
 Originally Posted by LaurV grrr... another silly problem... the formulation is unclear, where and whenever you can/may/must place signs, and what's happening if you don't... "while other seven-digit numbers simply cannot be solved, such as 0314157" 0+3-1+41+57=100 skip.
I don't think it was unclear. Your "41 + 57" is quite clearly forbidden by the problem statement: "Without changing the order or concatenating two or more digits into a larger number".

2017-06-06, 05:53   #10
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

22·2,423 Posts

Quote:
 Originally Posted by LaurV grrr... another silly problem... the formulation is unclear, where and whenever you can/may/must place signs, and what's happening if you don't... "while other seven-digit numbers simply cannot be solved, such as 0314157" 0+3-1+41+57=100 skip.
Well, that part he explained just fine --
Quote:
 Without changing the order or concatenating two or more digits into a larger number, use the basic operations and parentheses so that the answer of the mathematical equation is exactly 100.
"Concatenating" is too long of a word? I though that you Romans invented this word, so it shouldn't be lost in translation for you?

 2017-06-06, 06:01 #11 LaurV Romulan Interpreter     "name field" Jun 2011 Thailand 71×139 Posts Whoooops... Too fast a reading... the concatenated solution just jumped on my eyes from between the rows during I was skimming the text... Haha... Ok, I will look for a solution and send one... to make it up. It may take a while, our algorithms are always slower than yours...

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