







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. 





The board for a variant of chess 
20090316 

From Adam: I am trying to figure out how big a piece of wood I need for a variant of chess I thought up. The board essentially is a set of 6 concentric rings with an empty space in the center, each ring consisting of 24 spaces  so essentially 6 concentric 24sided polygonal rings made up of trapezoidal spaces. I know the interior angle of the shape (15 degrees), but I can't figure out the size this thing should be.
All I know is that the innermost ring will have the smallest spaces, and that those spaces need to be able to accommodate chess pieces 3/4" wide without them overlapping onto neighboring spaces. That is to say, the short parallel side of the trapezoidal space on the innermost ring should be at least 3/4". But I have no clue how to extrapolate the full diameter of the board from that one measurement. HELP!
Adam Goss
saganth@yahoo.com Answered by Stephen La Rocque. 





How many squares are there on a checkerboard 
20061217 

From Tania: how many squares are there altogether on the checkerboard (including the 64 small squares)? Answered by Penny Nom. 





Tiffany plays first board for her middle school chess team 
20021202 

From Patty: Tiffany plays first board for her middle school chess team. Since she joined the team last year, she has won 27 of 51 tournament games. That's a winning percentage of about 53%. If Tiffany went on a winning streak, how many games would she need to win in a row to raise her winning percentage to 60% Use variables and equations to communicate the method you've used to solve the problem. Answered by Penny Nom. 





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. 





8 Queens on a Chess Board 
20000606 

From Patrick McGarrity: In the classic puzzle where you put 8 Queens on a chess board and no queen can take any other queen, I was wondering if there was multiple solutions. Obviously there's the mirror and opposite images of the way I solved it, but I was wondering how many solutions there were, and if these solutions all followed a similar pattern? Answered by Claude Tardif. 





How many squares are on a chessboard? 
19991020 

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

