I think you have to say it like, "5 post-its per square, please paypal me 5 post-its for each square you pick." to not upset the force.
If naming the squares 1-100, starting with 1 in the upper left, working left to right, with 100 being the bottom right square, so that people can pick a square. I'm in for 4 squares as well - squares 11, 23, 36, and 48. Attached (just slapped a grid together).