Chess board?

[jamesravid]

Let me ask you a very familiar question,

How many squares are there on a chessboard? How many rectangles?

[psuresh1982]

Number of squares in a chessboard:

1^2 + 2^2 + 3^2 + 4^2 + 5^2 + 6^2 + 7^2 + 8^2 = 204.

Formula N = (n(n+1)(2n+1))/6

Number of rectangles in a chessboard:

There are 9 vertical lines and 9 horizontal lines. To form a rectangle
you must choose 2 of the 9 vertical lines, and 2 of the 9 horizontal
lines. Each of these can be done in 9C2 ways = 36 ways. So the number
of rectangles is given by 36^2 = 1296.

Formula N = (n(n+1)/2)^2

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suresh

[raj1402]

Number of squares in a chessboard:

1^2 + 2^2 + 3^2 + 4^2 + 5^2 + 6^2 + 7^2 + 8^2 = 204.

Formula N = (n(n+1)(2n+1))/6

mmm suresh are u sure thats 204 squares in chess board!!!

[psuresh1982]

If you have a doubt then work it out manually (first work it out 3x3 and 4x4) and let me know if it is correct or not.

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suresh

[raj1402]

ya suresh i go it now!!!

[dhivyamca]

squares-204

[jamesravid]

Right approach from Suresh. Hats off man

[rjroking]

no yaar.........chess board has 205 squares....coz chess board itself is also a square