Math Studying Advice

Question

Guys,

I am getting totally brutalized on math. I can't even get through basic 600 level problems, and it's not that I don't understand the math, I worked through the 5 MGMAT books and I understand the math in those, I just have no idea how to do the critical reasoning type questions on the GMAT. I studied Kaplan's strategies but that didn't really help much.

I put a list together of the subjects I don't really understand from the math forum tags, I was wondering if there were any guides on how to do these types of problems other than the "GMAT Math Book" thread. I'm ok on a basic level, but when they get more complicated I'm totally lost.

Combinations
 Probability
 Resources 
 Modules 
 Inequalities 
 Coordinate Geometry 
 Min/Max Problems 
 Mixture Problems 
 Rate Problems 
 Overlapping Sets 
 Work Problems 
 Sequences 
 Remainders 
 Graphs and Illustrations

missxmelon · Answer

Not sure if you've already done this, but I would go over the explanation for each question I got wrong and write down on a sheet of paper the "trick" or "concept" I missed. You should start seeing the same type of questions after doing a lot of practice questions, and hopefully you can take a look at that sheet and remember all the tricks.

Remember, sometimes you can work backwards with what you're given. Also, going through the math review in the Official Guide will help.

Remember, sometimes you can work backwards with what you're given. Also, going through the math review in the Official Guide will help.

BM · Answer

For me, I was awful in quant in all areas! Even after reviewing the Manhattan guides, I still struggled. So this is what I did:

1.  I re-read the Manhattan books, this time without doing the end-of-chapter questions.
 2.  I practiced with all of Jeff Sackmann's math sets.
 3.  GMATClub tests (all of them)
 4.  OG

After that, my quant scores were in the 48 t0 50 range. It took about two months to reach that level.

Bigred2008 · Answer

I currently have the Jeff Sackmann sets. When you finished reading the MGMAT books did you do the Jeff Sackmann set that corresponded to the book, i.e. MGMAT Number Properties - Sackmann Number Properties Fundamentals/Challenge? Because there are some of his sets I'm not completely sure which MGMAT book they correspond to. Any suggestions?

BM · Answer

Yes, sometimes Sackmann and Manhattan use different terms to describe the same topic, but rest assured that both sources cover the same material. It might take you a moment to organize everything correctly, but you will figure it out.

And, to answer your question, I did match Sackmann's math sets with the corresponding Manhattan math book.

And, to answer your question, I did match Sackmann's math sets with the corresponding Manhattan math book.

Izvos · Answer

How do you approach these questions? Do you use formulas? I can give you several books: Master The GMAT 2007 McGraw-Hill_s_GMAT,_2008_Ed Nova's GMAT Prep Course Official Guide - 10th Edition. Lets try division with remainer. Please read thi explanation and tell me what you don't understand Quetion. Integer m has 4 different prime factors and n has 3 different prime factors. If m and n has the greatest common factor of 15, how many different prime factors does mn have? (A) 4 (B) 5 (C) 6 (D) 7 (E) 8 Generally, “the remainder is r when x is divided by y” means x = y × q + r, r < the integer q is called quotient, the integer r is called remainder, and the integer y is called the divisor. One more way to express the same idea is x = r(mod y). For instance, “The remainder is 1 when 7 is divided by 3” means 7 = 3 ⋅ 2 + 1 or 7=1(mod 3). Dividing both sides b of x = y × q + r by y gives the following alternative form Q = q + . Notation X = 4q + 2 Is a general expression of the integer X that leaves remainder 2 when divided by 4. Giving q different integer values: 0, 1, 2,… one can find all such numbers: 2, 6, 10, … All in all, the latter expression means, that beginning with 2 every fourth number leaves remainder 2 when divided by 4. Thus, 2 is the least such number. Note: r is the least number that leaves remainder r when divided by every integer greater, than r. Consider the following problem: The integer X leaves remainder 2 when divided by 4 and remainder 1 when divided by 3. On the GMAT one of three types of tasks will follow: a) Find the least possible X. b) Find one general rule for X. c) Find the number of such integers in a certain interval. Explanation: a) First of all, interpret the statement of the problem as follows: X = 4a + 2 and X = 3b + 1 Note: Be sure to use different variables for quotients in different rules. Secondly, write out the equation 4a + 2 = 3b + 1 and express b through a: b = 4a + 1 3 . We choose to express b, because its coefficient is less then the one before a. Thirdly, try different whole values (0, 1, 2,…) for a until b becomes the integer. In our case: for a=0, b=1/3 – not integer, for a=1, b=5/3 – not integer, for a=2, b=3 – integer. Thus, a = 2 and b = 3 are the least possible values of a and b to integers simultaneously. Finally, substitute a for 2 in the rule for X (or b for 3, which yields the same X): X> = 4 × a> + 2 = 4 × 2 + 2 = 3 × 3 + 1 = 10 Ten is the least possible X, that leaves remainder 2 when divided by 4 and remainder 1 when divided by 3. Thus, X> = 10. b) In order to obtain the general rule for X use the following formula: X = LCM(d", d# c + X> where d", d# – the divisors, X> - the least possible X. In our example: LCM3, 4) = 12 and X> = 10. Hence, X = 12c + 10. c) Let’s find out, how many integers with the required properties there are between 100 and 150. 100 < 12 + 10 < 150, 90 < 12 < 140, 7.5 < < 11. (6). Since c is an integer, there are 4 possibilities: c= 8, c=9, c=10 or c= 11, thus the answer is 4.

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