Number Properties GMAT Strategy Guide, 4th Edition (Manhattan GMAT Preparation Guides)

I scored 750 (49, 42) on the GMAT and from experience, high GMAT score is not about tricks or solving thousands of questions - it is about having a strong foundation. Arithmetic is critical for the GMAT - close to 50% of quant questions you encounter will rely on arithmetic to solve. If you are rusty with math (primes, powers, roots, etc), this is one of the best books to refresh the basics of Arithmetic without spending months on it. Besides review, it also lists ways to save time on calculations. The faster you can do easier questions, the more time you have for the hard ones, and those are the ones that count on the GMAT.

Pros:
- This book comes with a code that provides access to 6 Manhattan GMAT tests for free ($45 value; online access)
- The book is split into 2 sections - basic and advanced, which is a better approach than dumping everything at the same time. By covering 2 separate sections for basic and then in the second half of the book advanced...Read more

"Very good for the target audience" - I think this sums it all. If you are someone who has not done active maths for some time now, and therefore does not remember the concepts involved very well, this is the book for you. This I will say holds true for most of the books of the Manhattan Quant series.
The Manhattan Quant series books cover the concepts only to the degree that gets asked in the GMAT, and do not overwhelm you.
Plus, as each of the Manhattan books then turns to the Official Guide for practice, each of the books has a section where the appropriate questions for that topic are numbered from the OG. They also detail the toughest of the lot from OG. Here I think the book is useful for anyone, irrespective of the personal comfort level with maths.
Therefore if you are true to yourself and practice the questions marked from OG as you go along, this would prove to an excellent resource for cracking the quant part of the GMAT.

The Manhattan GMAT quantitative guides are great for reviewing or just flat out learning the quant concepts tested on the GMAT. Don't let the thinness of the books fool you; they efficiently pack in alot of material and do not pad the books with lots of practice questions created by them. It's far better to work off of Official Guide questions, and each Manhattan GMAT guide has a handy list of all OG questions subdivided into Problem Solving & Data Sufficiency, and further subdivided according to the concept tested. There is an additional problem set of the most challenging OG questions spanning all concepts. I am decent, but rusty at math, and after using a couple of the Manhattan GMAT quant guides, was able to improve my quant score from high 40s on practice tests to 51 on the real thing! I can't recommend these books enough.