The book contains 200 excellent Thermometers puzzles 11x11.Medium puzzles 100 Hard puzzles 100 All riddles have only 1 solution. 2 puzzles per page. The font size is correct you will not have to strain your eyes when solving puzzles.High quality paper and print (all puzzles read well, easy to write with pen and pencil without worry of bleed-through). Thermometers is a kind of logic puzzles. Its rules are simple, but insight and subtle reasoning are needed to solve it. The grid is filled with thermometers, which are either not filled, partly filled or completely filled. The numbers on the outside indicate how many squares are filled in that row or column. Every thermometer is filled from the base (circular part), towards the top. This does not depend on the actual orientation of the thermometer.