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Rooks on a chessboard (Posted on 2018-11-26) Difficulty: 2 of 5
How many ways are there to place two rooks on the same column or same row on a nxn chessboard?

See The Solution Submitted by Ady TZIDON    
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Solution correcting a typo in puzle's solution Comment 4 of 4 |
correcting  a  typo  in  puzzle's  solution:

LAST LINE IN THE OFICIAL SOLUTION SHOULD BE
 4*(n^3-n^2) ways   since  1+1+2=4

2 white rooks n^3-n^2 ways 
2 black rooks n^3-n^2 ways 
1 white and 1 black rooks 2* (n^3-n^2 ) ways 

answer:  4 * (n^3-n^2 ) ways

Edited on November 30, 2018, 9:39 am
  Posted by Ady TZIDON on 2018-11-30 09:37:45

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