Maths Question?

Shrimp

Hi,

I know this isn't exactly a question, It's more of a puzzle. Anyway here it is!



The idea is to get all the horizontal rows & vertical rows to include the numbers 1,2,3,4,5,6,7,8,9. As there are only nine boxes on each row you can't have any number repeat!

For example... If you look at the top left hand corner it looks like this: 4 Blank Blank 1... If i decide to put a 3 after the four I can't because as there is already a 3 on that vertical row. If you follow the row down you can see that the 3 is already on that row. In order to make put a valid number in that blank, It must not be on the vertical or horizontal rows.. one that would fit there is a 6... not to say that that is the correct number...

If you have any questions please ask.

There is only one possible formation of numbers that will work.. It is doable, I have yet to do it though!

Good luck and Godspeed!

P.S. Post your attempts as it will help ppl to know what not to do! It only takes one number to mess it all up!

Shrimp

The pic is working now!

Shrimp

Oh sorry one other thing... I'd advise that u would print out a couple of these and when your doing it! use a different colour pent to the font, just so you can clearly see which numbers you have added...

Sev

Ok.. maybe I dont really understand what youre supposed to do.. but from what I think gather it seems very easy. Surely this works right? or am I missing something important

1,2,3,4,5,6,7,8,9
2,3,4,5,6,7,8,9,1
3,4,5,6,7,8,9,1,2
4,5,6,7,8,9,1,2,3
5,6,7,8,9,1,2,3,4
6,7,8,9,1,2,3,4,5
7,8,9,1,2,3,4,5,6
8,9,1,2,3,4,5,6,7
9,1,2,3,4,5,6,7,8

Shrimp

how could that work... if you look at what you have as the top left hand number...1 while in the pic i supplied it's a 4.. thats definatley wrong!

Sev

Oh right.. you finish off the grid, I thought the picture was just an example for explanation. I'll have a go then

Shrimp

ok cool... anyone else wanna give it a shot! :D:D:D:D:D

sionnach

easy enough, simple cancellation. Here's my solution, i think it's right:

http://members.boards.ie/sionnach/solution.gif

Shrimp

how did you go about doing it? like... what was the calculation?

sionnach

well for each empty box put in the numbers it could possibly be, ie all the numbers 1-9 not sharing a row or colum with it. When you've that done you can look for unique possibles in each row or column, ie: if theres a posible 5 in one box but nowhere else in that row, that box must contain a five, and you may cancel the 5's in the rest of the boxes in that column and vice versa for finding a unique possible number in a column. Cancelling those 5's will reveal another unique possible or possibles and so on and so on. You get a chain reaction of uniques being revealed and eventually you're left with one number in each box

Shrimp

Exactly... i went along that route.. but i must have messed up along the lines... I got like 6 colums done then it messed up! Where did you start on it? like which number?

Shrimp

well?

sionnach

very last row, near the right

Shrimp

Oh yeah.. I had a shot at it today and got it without lookin at the answer! Thanks