Chess with Maths

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Mr_Mathematician

🎯Brain teaser ‼️

  • In how many ways two queens shall be placed into 8×8 chessboard such that they never get cancel by each other ( there are only two queens on board place).Cancel means possibilities of capture.

Can you answer this question with logic?  

Ashvath23

This question is based on permutation concept ? Am I correct ?

LITO13mtz
What is this word "maths"?
LordHunkyhair3

Well in the old Scots math means good, so...

Ashvath23

I think so, there are two queens and 64 squares , According to me the answer would be 2^8 .

Mr_Mathematician
Ashvath23 wrote:

This question is based on permutation concept ? Am I correct ?

Yes

Mr_Mathematician
Ashvath23 wrote:

I think so, there are two queens and 64 squares , According to me the answer would be 2^8 .

No

Suppose you have placed your queen on a1 then for another queen to arrange position no neither a square nor 1 square file and the diagonal square would be left for another queen

You have counted all the cases 
Ashvath23

So, the better way to solve this would be , to left either queen untouched and move another queen , so this will happen in every square on the board , such that it cover all the square and positions .

Ashvath23

We can observe that in some cases the numbers are increasing and decreasing .

Atharv8849

Hello

Nice to see you after long time...

Wind

I've always tried to do this on a chessboard but never could!

At max I could put 7 queens not attacking each other, 8 is very hard.

Yet, very surprised that there are 42 ways 🤯

Mr_Mathematician
Optimissed wrote:

There are 42 ways the Qs can be placed with the white Q on a1. There are 42 ways if the white Q is on a4. If the white Q is on f4, there are 38. Logically, for all the edge squares there are 42. If on b7 there are 40, so a pattern is developing. If we divide the board into concentric tracks, the outer track contains squares all of which are 42. The next track inwards 40, the next track inwards, 38.

The final track is the centre four squares. Taking one at random, d4, there are 5x6 +6 = 36

So we have 4x36 + 12x38 + 20x40 + 28x42 = 2576

Double it and we have the answer.

5152

Yes correct and you logically proved 👏

Congrats

Mr_Mathematician
Wind wrote:

I've always tried to do this on a chessboard but never could!

At max I could put 7 queens not attacking each other, 8 is very hard.

Yet, very surprised that there are 42 ways 🤯

I think you misunderstood the question , there are only two queens on board

Mr_Mathematician
Ashvath23 wrote:

We can observe that in some cases the numbers are increasing and decreasing .

Yes

StockOfHey

Isn't it just a multiplication problem?

StockOfHey

(64 - (8*3))*64 = 2560?...

StockOfHey

Oh... I changed my mind...

magipi

Just out of curiosity, what does "never get cancel by each other" mean in the puzzle? Everyone seems to understand it, but I don't.

StockOfHey

(64 - (8*3))*7 = 280

(64 - (8*3) -((2*1+3*2+4*3+5*2+6*1)/9))*9 = 324

(280 + 324)*4 = 2416?

Ashvath23
magipi wrote:

Just out of curiosity, what does "never get cancel by each other" mean in the puzzle? Everyone seems to understand it, but I don't.

It means that the both queens won't capture each other . Both queens are in safe squares.