(Q). Find the number of rectangles in a chess board of 12×14 grid instead of 8×8 grid.
Solution:-
2 lines can be selected from 12 parallel lines in ¹²C₂ ways.
2 lines can be selected from 14 parallel lines in ¹⁴C₂ ways.
Hence number of rectangles = ¹²C₂×¹⁴C₂ Answer