Olympiad workbookIOQMPermutation and Combination
What is the number of ways in which one can choose 60 units square from a 11 11 chessboard such that no two chosen square have a side in common ?
Correct answer
62
Step-by-step solution
Either select 60 black squares from 61 black square or select all 60 white squares Total equal to ⁶¹ C ₆₀+ ⁶⁰ C ₆₀=61+1=62