made easy adv mock

Question

the number of ways in which we can place 3 white pawns and 3 black pawns on a 3*3 chessboard

my answer was 12.

approach :- we cant have any 2 black pawns or 2 white pawns in the same row or column

{3*2*1} * {2*1 * 1}

am i correct??

Comments

what is wrong with this method…

Initially the chess board is empty, so I can place the 1st pawn in 9 ways, now 8 places are left and I can place the 2nd pawn in 8 ways and so on, the last pawn can be placed in 4 ways.

So total  = 9*8*7*6*5*4

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@abhineet, divide the total by 3! due to 3 white pawns are identical. Then again divide it by 3! due to 3 black pawns are identical.

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ok got it, I forgot missed the point of them being identical.