+0  
 
0
626
1
avatar

Let's play mini-Sudoku!

 size(3cm); draw((0,0)--(4,0)--(4,4)--(0,4)--cycle,black+2bp); draw((0,2)--(4,2),black+2bp); draw((2,0)--(2,4),black+2bp); draw((0,1)--(4,1)); draw((0,3)--(4,3)); draw((1,0)--(1,4)); draw((3,0)--(3,4));

We wish to place an "X" in four boxes, such that there is exactly one "X" in each row, column, and 2x2 outlined box. For example:

 size(3cm); draw((0,0)--(4,0)--(4,4)--(0,4)--cycle,black+2bp); draw((0,2)--(4,2),black+2bp); draw((2,0)--(2,4),black+2bp); draw((0,1)--(4,1)); draw((0,3)--(4,3)); draw((1,0)--(1,4)); draw((3,0)--(3,4)); label("X",(0.5,1.5)); label("X",(1.5,3.5)); label("X",(2.5,2.5)); label("X",(3.5,0.5));

In how many ways can we do this?

 

Please explain very well in this quesiton.

Guest Mar 18, 2015

Best Answer 

 #1
avatar+92751 
+10

I think this is it

 

1)  there are 4 choices for the first row, the X can go anywhere.    Just put your X in

2)  There are only 2 choices for the next row because it cannot go in the same box as the first one did.

3)  There are 2 choices for the next row because it can go in either box but it cannot go under either of the 2 x's that are already there.

4)  There is only one possibility left for the last row

 

so the number of possibilities is        4*2*2*1=16

Melody  Mar 19, 2015
 #1
avatar+92751 
+10
Best Answer

I think this is it

 

1)  there are 4 choices for the first row, the X can go anywhere.    Just put your X in

2)  There are only 2 choices for the next row because it cannot go in the same box as the first one did.

3)  There are 2 choices for the next row because it can go in either box but it cannot go under either of the 2 x's that are already there.

4)  There is only one possibility left for the last row

 

so the number of possibilities is        4*2*2*1=16

Melody  Mar 19, 2015

8 Online Users

avatar
avatar

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.