Be amazed at the optical illusions, tricks with numbers and games to play at home. Just in case you get stuck, each book has a chapter detailing helpful tips to solve the mind- boggling games plus answers with full explanations. It all makes for an amazing and unforgettable challenge devised by one of the greatest puzzle experts in the world today! ARE YOU SITTING COMFORTABLY? For this fantastic collection of household and classroom challenges you only need everyday objects that are easy to find. So take a seat, get comfortable and prepare for a range of perplexing puzzles and testing tasks.