The Mammoth Book of IQ Puzzles
"With this brain-teasing new collection of tantalising puzzles and top-grade
problems, Nathan Haselbauer, mastermind behind the test for the world's most
intelligent person, throws open an irresistible challenge to all.
The puzzles vary from math and logic problems to word games, with the emphasis
on clarity of presentation and elegance of answer. Covering a broad spread of
difficulty, they range from the surprisingly easy to a level of difficulty that
will fox even the world's most devious minds. Although each puzzle is capable
of being solved in just a few minutes, this is a puzzle collection like no
other that will stretch your brainpower to its limits."