View unanswered posts | View active topics It is currently Sat Dec 16, 2017 9:23 am



← Back to the Calcudoku puzzle page




Reply to topic  [ 25 posts ]  Go to page 1, 2, 3  Next
 Subtraction and Division with 3 or more squares 
Author Message

Posted on: Sat May 14, 2011 4:59 pm




Posts: 8
Joined: Fri May 13, 2011 1:15 am
Post Subtraction and Division with 3 or more squares
Before discovering the puzzles on this site, I had only seen the - and / operators with 2 squares. I had assumed this would be the case since multiplication and addition are associative operations whereas subtraction and division are not. Has anyone else felt confusion over the quotient of 4,8,2 for example? I see a potential ambiguity with (8/4)/2 = 1, 8/(4/2) = 4, 4/(2/8) = 16, etc.

Anyway, after solving many of these puzzles, it seems that the convention is to always subtract and divide in descending order. Is this correct?


Profile
User avatar

Posted on: Sat May 14, 2011 5:15 pm




Posts: 422
Location: Canada
Joined: Fri May 13, 2011 2:43 am
Post Re: Subtraction and Division with 3 or more squares
Dividing or subtracting in descending order is mostly correct although it can be either 8/4/2 or 8/2/4. The highest number goes in the front.

Or really, it can be any order but without using brackets. The highest number must be the first one if you want a non-fractional or non-negative result.


Profile

Posted on: Sat May 14, 2011 6:23 pm




Posts: 8
Joined: Fri May 13, 2011 1:15 am
Post Re: Subtraction and Division with 3 or more squares
That make sense, thanks. I suppose I can't go wrong with highest number minus the sum of the others and highest number divided by the product of the others.


Profile

Posted on: Tue May 17, 2011 7:16 pm




Posts: 2
Joined: Fri May 13, 2011 5:08 pm
Post Re: Subtraction and Division with 3 or more squares
Any order is OK as long as the result is a non negative integer. Sometimes a different order gives different results, like 9,3,3: (= either 9 or 1) . As long as one of the results fits, it is OK.


Profile

Posted on: Tue May 17, 2011 7:20 pm




Posts: 20
Joined: Mon May 16, 2011 7:17 pm
Post Re: Subtraction and Division with 3 or more squares
richr wrote:
Any order is OK as long as the result is a non negative integer. Sometimes a different order gives different results, like 9,3,3: (= either 9 or 1) . As long as one of the results fits, it is OK.

That's not true. 9 3 3 only yields 1 as answer, not 9 (I think you meant 9/(3/3) = 1?)

The best way to solve this problem is as sneaklyfox already said, to not use brackets and always put the numbers in descending order.

_________________
Confucius say - 'He who stands on toilet is high on pot.'


Profile

Posted on: Tue May 17, 2011 9:49 pm




Posts: 8
Joined: Fri May 13, 2011 1:15 am
Post Re: Subtraction and Division with 3 or more squares
maartensmit wrote:
The best way to solve this problem is as sneaklyfox already said, to not use brackets and always put the numbers in descending order.


I just thought of an exception to descending order with division, but only when 0 is possible. If 3 squares are labeled 0/, you know the order of division will be 0/x/y (obviously not descending).


Profile

Posted on: Tue May 17, 2011 9:53 pm




Posts: 20
Joined: Mon May 16, 2011 7:17 pm
Post Re: Subtraction and Division with 3 or more squares
larryb33 wrote:
maartensmit wrote:
The best way to solve this problem is as sneaklyfox already said, to not use brackets and always put the numbers in descending order.


I just thought of an exception to descending order with division, but only when 0 is possible. If 3 squares are labeled 0/, you know the order of division will be 0/x/y (obviously not descending).

Ah, yes, that is true. I didn't think of that, I always skip the puzzles with zero :lol:

_________________
Confucius say - 'He who stands on toilet is high on pot.'


Profile
User avatar

Posted on: Wed May 18, 2011 1:45 am




Posts: 422
Location: Canada
Joined: Fri May 13, 2011 2:43 am
Post Re: Subtraction and Division with 3 or more squares
maartensmit wrote:
9 3 3 only yields 1 as answer, not 9 (I think you meant 9/(3/3) = 1?)


9/(3/3) = 9/1 = 9 But anyway, the puzzles don't work like that. No brackets.

As for the zero puzzles, you have to forget that there is such a thing as x/0 = infinity because the puzzles do allow you to have more than one zero in a 0: box (in L configuration, for example). Assuming that none of the puzzles operate with brackets, that should not be possible. So you can treat 0/0 = 0.


Profile
User avatar

Posted on: Thu May 19, 2011 11:28 am




Posts: 2215
Joined: Thu May 12, 2011 11:58 pm
Post Re: Subtraction and Division with 3 or more squares
sneaklyfox wrote:
9/(3/3) = 9/1 = 9 But anyway, the puzzles don't work like that. No brackets.

As for the zero puzzles, you have to forget that there is such a thing as x/0 = infinity because the puzzles do allow you to have more than one zero in a 0: box (in L configuration, for example). Assuming that none of the puzzles operate with brackets, that should not be possible. So you can treat 0/0 = 0.


Spot on in both cases. No brackets are involved, and you can't do division by zero (so a cage with 3 cells
can never have 2 zeroes, for example)

Patrick


Profile
User avatar

Posted on: Fri May 20, 2011 2:57 am




Posts: 422
Location: Canada
Joined: Fri May 13, 2011 2:43 am
Post Re: Subtraction and Division with 3 or more squares
Can't have two or more zeros in a cage? Ok, maybe I forgot. I just thought maybe that had happened. Maybe it was 0x.


Profile
Display posts from previous:  Sort by  
Reply to topic   [ 25 posts ]  Go to page 1, 2, 3  Next

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron
All forum contents © Patrick Min, and by the post authors.

Forum software phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by STSoftware.