7/10
This book is actually a collection 150 mind bending puzzles, with solutions. There are number of problems that are based on concepts that include: Time, Money, Distance, Age and other such topics, with various difficulty levels; along with pure logical, and intuitive kind of puzzles. And these puzzles are pure entertainment to solve.
Shakuntala Devi was an Indian writer and mental calculator, popularly known as the 'human computer'. She has many accolades to her name: in 1977, at Southern Methodist University in Dallas, she extracted the 23rd root of a 201-digit number in 50 seconds, beating a Univac computer, which took 62 seconds. Three years later, she earned herself a spot in the Guinness Book of World Records when she multiplied two 13-digit numbers (7,686,369,774,870 and 2,465,099,745,779) *and* articulated the solution (26-digits: 18,947,668,177,995,426,462,773,730) in just 28 seconds.