#
# There exists a grid of 10 squares by 20 squares. Find out the total number different rectangles possible?

Is this perhaps homework? There is a homework board on the education board.
If so : how do you intent to approach this question yourself?
Once you answer that, we'll take it from there !

Hint : remember that every square is a rectangle but every rectangle is not a square. Answer is very simple...

My answer: 7560

ANS = C(9,2) * n(n+1)/2 where n= 20
= 7560


is it correct?

I hope u people don't mind replying atlst whether it was crrct or not? N if I was wrong. HOW?

I got 11,550. Not sure why you have the C(9,2) term in there. You're on the right track with the n(n+1)/2 for n = 20; but you should have an additional term in there for n = 10. Remember that a 2x 3 rectange is not the same as a 3x2.