The puzzles in this collection of treacherously difficult puzzles will stretch even the most advanced Su Doku enthusiast. You will need to use all of your best solving techniques to get to the end of this testing challenge. The puzzles in the collection are of the highest quality and are perfect for the advanced solver in need of a constant supply of ultra-difficult puzzles. Guaranteed to provide hours of mind-stretching entertainment.

Codeword Puzzle Book for Adults Codewords (sometimes called Code Breakers) are like crosswords with no clues. Instead, every letter of the alphabet has been replaced by a number, all you have to do is decipher which letter is represented by which number. This Codeword Puzzle Book is a fun way for teens, adults or seniors to sharpen their minds and test their Logic Skills. Including 90 Puzzles to keep you entertained for hours. This is the UK English Spelling version. Codeword Puzzle Book Features: Loads of Puzzles 90 Pages of Puzzles Suitable for Most Levels Medium to Hard Difficulty Perfectly Sized - 7" x 10" Solutions Can be Found at the Back of the Book Premium Matte Color Cover Puzzle King Publishing: Puzzle Books for Everyone!

Accessible but rigorous, this outstanding text encompasses all of the topics covered by a typical course in elementary abstract algebra. Its easy-to-read treatment offers an intuitive approach, featuring informal discussions followed by thematically arranged exercises. This second edition features additional exercises to improve student familiarity with applications. 1990 edition.

Codeword puzzles are simple to play and utterly addictive. If you enjoy cracking codes, this puzzle book is for you. The letters of the alphabet are hidden in a unique code. Each letter of the alphabet is represented by a random number, from 1 through 26. Some letters are already given. With these to get you started, you must fill in the grid. Contains over 160 puzzles. Answers found in the back of the book. Spiral bound, 192 pages.

David Joyner uses mathematical toys such as the Rubik's Cube to make abstract algebra and group theory fun. This updated second edition uses SAGE, an open-source computer algebra system, to illustrate many of the computations.

This challenging visual puzzle will appeal to lovers of logic and deduction brain teasers. How To Play: A map grid shows two towns, typically A and B. The objective of the puzzle is to lay down tracks to connect the two towns. Numbers around the outside of the grid tell you how many pieces of track are to be placed in each row and column. You can only use straight (horizontal and vertical) and curved (right and left) rails and the track cannot cross over itself. There is something very satisfying in the laying down of tracks. The puzzles are arranged with varying levels of difficulty, where difficulty is largely dependent on the size of the map grid (from 6x6 to 10x10). Puzzles included cover three levels of difficulty: 70 Easy, 70 Moderate, and 60 Difficult.