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 July 8th, 2019, 11:14 AM #1 Newbie   Joined: Feb 2018 From: California Posts: 19 Thanks: 1 Placing Operation Signs to Make an Equation Can you help me figure out this question? Place the signs +. -, and = between these digits to make an equation. You can change the order of the signs, but you must use each sign only once. 4 8 3 3 6 9 Last edited by skipjack; July 9th, 2019 at 05:15 PM.
 July 8th, 2019, 01:42 PM #2 Global Moderator   Joined: May 2007 Posts: 6,786 Thanks: 708 Impossible. No matter how you group them, there will be an odd number of odd numbers on one side and and even number of odd numbers on the other. Using + or - will always end up netting a number with the same parity as the number of odds. Thanks from mjsilverfly
 July 9th, 2019, 02:01 AM #3 Senior Member   Joined: Apr 2014 From: UK Posts: 936 Thanks: 335 Did you mean 48 - 3 = 36 + 9 ? Thanks from topsquark
 July 9th, 2019, 02:02 AM #4 Global Moderator   Joined: Dec 2006 Posts: 20,823 Thanks: 2160 48 - 33 = 6 + 9 or 48 - 3 = 36 + 9 Thanks from topsquark
 July 9th, 2019, 08:29 AM #5 Newbie   Joined: Feb 2018 From: California Posts: 19 Thanks: 1 Oooooh! Yes!! Thank you, thank you!! Clever!
July 9th, 2019, 01:21 PM   #6
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Quote:
 Originally Posted by mjsilverfly Oooooh! Yes!! Thank you, thank you!! Clever!

July 9th, 2019, 11:19 PM   #7
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Quote:
 Originally Posted by mathman Your original statement was ambiguous.
Given that you can use each sign only once and that the numbers must remain in the same order, there are a limited set of options, I'm not convinced it's ambiguous. If it is ambiguous, could you explain for those of us who may not have noticed?

July 10th, 2019, 06:22 PM   #8
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 Originally Posted by weirddave Given that you can use each sign only once and that the numbers must remain in the same order, there are a limited set of options, I'm not convinced it's ambiguous. If it is ambiguous, could you explain for those of us who may not have noticed?
Allowing lumping. Must remain in same order?

 July 10th, 2019, 11:50 PM #9 Senior Member   Joined: Apr 2014 From: UK Posts: 936 Thanks: 335 I see what I've done now. Given there are only 3 symbols which can be used only once, this would imply lumping of digits. I can't see anything which implies the digits must remain in the same order, I think I assumed that since we are told that the order of symbols may change, this means the numbers aren't otherwise that would have been mentioned too, but this isn't necessarily true. Thanks for making me think
July 11th, 2019, 01:37 PM   #10
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Quote:
 Originally Posted by weirddave I see what I've done now. Given there are only 3 symbols which can be used only once, this would imply lumping of digits. I can't see anything which implies the digits must remain in the same order, I think I assumed that since we are told that the order of symbols may change, this means the numbers aren't otherwise that would have been mentioned too, but this isn't necessarily true. Thanks for making me think
I missed the point of "only once" needed to force lumping.

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