







Four dots are randomly placed on an 8x8 grid 
20100226 

From bobbym: Four dots are randomly placed on an 8x8 grid, compute the probability
that no row or column contains more than one dot. Answered by Claude Tardif. 





Grain of rice on a chess board 
20090330 

From andy: Is there an easy way for my students to find out 8 to the power of 21 to solve the grains of rice doubling investigation on a chessboard? Any suggestions welcome. Thanks very much Answered by Robert Dawson and Claude Tardif. 





Squares on a chess board 
20010411 

From Tom: It was once claimed that there are 204 squares on an ordinary chessboard (8sq. x 8sq.) Can you justify this claim? "PLEASE" include pictures. How many rectangles are there on an ordinary chessboard? (8sq. x 8sq.) "PLEASE" include pictures. Answered by Penny Nom. 





How many squares are on a chessboard? 
19991020 

From Tchilco: How many squares are on a chessboard? Answered by Penny Nom and Claude Tardif. 

