Aptitude Preparation Offline is completely offline free aptitude reference book with concepts to learn and master and test your Aptitude and Reasoning skills, covering a wide range of grammar topics. Topics Included. 1. Numbers. 2. Permutations and Combination. 3. Odd man out. 4. Compound Interest. 5. Problems on trains. 6. HCF and LCM. 7. Simple Interest.