One in a million -- Math magic -- Cooperative problems -- Lots of dots -- Average pentominoes -- Distributing tiles -- Guess my rule -- The rice problem -- Lines, squares, cubes, and hypercubes -- Fractional salaries -- A temperature experiment -- Circular reasoning -- Coins for compassion -- Toothpick rectangles -- The stairs problem -- Gumball boxes -- The medicine experiment -- Fabulous fractals -- Triangular tessellations -- Kaleidocycles.