If math concepts are just not registering...

What helped me the most was reviewing the concepts with a reliable guidebook and immediately reinforcing that material with question practice.

For me, solely doing questions and then checking the answers was not enough. I could understand that problem, but maybe not variants of it. I didn't see the overall concept sometimes. But a guidebook by itself is also incomplete. By the time I finished the book, I forgot most of it.

Everyone is different, but try question practice alongside a guidebook if you haven't done so.

Well its pretty obvious that concepts take time to cement in your mind if they are new or you haven't touched them for a while. That is why we practice, so that the concepts become second nature to us.

Things you can do:
1. Prepare your own notes/flashcards/cheat sheets. While studying write down critical concepts and formulae in a fresh notebook in your own handwriting and keep it handy at all times. Then you can always check out the flashcards available online and add the extra concepts as dope.
2. Whenever you are practising keep that notebook open in front of you. And see the concepts that you can use.
3. Avoid mugging up too many formulas. Rather learn how to derive them. MGMAT does a good job in this. You will be more comfortable, especially on DS questions.
4. Even during a mock test, keep your notebook with you and look up a critical concept if you cant remember. By doing so, believe me you will never forget that concept.

Remember, just knowing the concepts is not enough but being able to apply them correctly is. I must have at least 50-60 pages filled with critical quant concepts, but I know 90% of them and will never forget them for the rest of my life.

IMHO I think what you are talking about is not concepts but more of manipulations. You cannot mug up manipulations. And Inequalities and Combinatorics are considered some of the more difficult concepts because there isn't a universal one single way of solving them that everyone is comfortable with.

For inequalities - I usually use numberline or algerbraic approach or number plugging or a combination of either.
For Combinatorics - Hard Cold Basics. And a hell lot of practice.

Hope this helps. Practice is the key!

I appreciate the responses alot.

I actually began with the OG12, but I'm considering putting it on hold to buy the all five Quantitative Manhattan books and completing those.

What do you guys think? Bad/good idea?

The Manhattan math series is very good. Using those books alongside the OG will allow you to get more value out of question practice.

So, my answer is: good idea.

You already haven't done that??!! No wonder you are struggling. GET THEM ASAP!!

Yeah, it was a big mistake on my part to simply "jump" right into the GMAT OG12.

I wasted the diagnostic test and about 75 of the PS questions. I've put an immediate hold on utilizing it further. I ordered the entire set of 8 Manhattan books online and will be starting them as soon as they arrive. Until I fully grasp every single concept, the OG12 will be collecting dust in the corner of my desk.

Thanks for the help guys!

A small word of caution - the OG has excellent examples for Verbal, but I'd probably say that the GMAT math is a bit harder than the OG quite substantively. So take that with a grain of salt and proceed one step at time.

I will not be the right person to advice Quant...But it will not HURT anyone, right ?

If you have forgot the basics, first BRUSH the basics from any good Maths books.
Start to solve questions from each topic for PS/DS.
Identify if you are weak in any specific area or in the format (say - DS)
Attack the weakness by concentrating on that area....

Understand the concepts - Apply them - Find what is the best approach for you.
example - I like to approach the problem in a manner that is easiest and fastest for me. It will be different from the normal approach, but does not matter (different from OG, but much better and efficient)- After all there is no ambiguity/style/etc in Quant....

Once you have practiced a lot and fine-tuned different approaches - You can go to the next level - See the problem. Pause for a moment (5-15 secs) before solving when you can identify the best way to solve the problem - Solve it - Sometimes when you will not get a solution/you guesstimate before solving that it will be time-consuming to solve the normal way - Then you can plug-in Ans. choices/apply many of the alternative strategies....

After all you know what will work the best for you !!!