GMAT Strategy

* you should follow the following PROBLEM SOLVING HIERARCHY for ALL quant problems.
in order for you to proceed through the quant section without wasting excessive time (and therefore not finishing), you MUST stick to the following hierarchy - and, most importantly, you MUST MOVE ON TO THE NEXT STEP AS QUICKLY AS POSSIBLE IF YOU DON'T FIND A METHOD THAT WORKS FOR THE CURRENT STEP.
here's the hierarchy. it works slightly differently for problem solving than for data sufficiency, with most of the differences having to do with "plugging in numbers":


PROBLEM SOLVING:

1. can i find a "textbook method" to solve the problem?
- i.e., can i find an 'opener' that might be in an answer key, etc.?
IF NOT,
2. can i "plug in numbers" (for equation or word problems), or just LIST things (for counting or probability problems)?
- note that there are two kinds of "plugging in numbers" for problem solving:
(a) plugging in YOUR OWN numbers, and working through the problem in the normal direction with your numbers instead of variables (VIC style problems),
(b) plugging in the ANSWER CHOICES and working the problem backwards (used if the answer choices are numbers and there's a decently easy path "backwards" through the problem).
IF NOT,
3. can i estimate, or perform process of elimination in any other way?
- if the answer choices are NUMBERS and there's a decent spread - i.e., not all of the answer choices are extremely close together - then you may be able to eliminate answers based on estimation. this goes especially for geometry problems, which have DIAGRAMS and are therefore easier to estimate, but it goes for all sorts of other problems as well.
IF NOT,
4. guess
- if you get to this point, DO NOT DELIBERATE - just guess. remember that any random guess is as good as any other random guess. if you're an extreme "deliberator", then, as weird as it may sound, you may want to have an actual method for random guessing. this could be as simple as "pick the first one of the remaining choices", but anything you can do to prevent staring at the problem is good.


DATA SUFFICIENCY:

1. can i find a "textbook method" to solve the problem?
- i.e., can i find an 'opener' that might be in an answer key, etc.?
IF NOT,
2. can i "plug in numbers"?
- note that NUMBER PLUGGING WORKS DIFFERENTLY FOR DATA SUFFICIENCY. with problem solving, all you have to do is plug in one set of numbers (VICs) or plug in one answer choice at a time (working backwards). with data sufficiency, though, you have to plug in MULTIPLE numbers or sets of numbers, with the goal being to TRY FOR 'INSUFFICIENT'.
in other words, you should try multiple values, with your goal being to get both a 'yes' and a 'no' (if it's a yes/no question) or two different values (if it's a value question).
if it's a number properties problem, you should make sure that you figure out the TYPES of numbers being tested, and plug in accordingly. for instance, if the problem involves absolute values, then it's likely that you'll have to plug in both positive and negative numbers.
IF NOT,
3. can i use the "easy statement", or perform process of elimination in any other way?
- always use the "easy statement" first, if there is one. this is essential for time management: you want to eliminate as many answers early as possible, in case time runs short.
ironically, the hardest problems commonly have one very "easy" statement out of the two (such as a statement that doesn't contain one of the relevant variables).
IF NOT,
4. guess
- if you get to this point, DO NOT DELIBERATE - just guess. remember that any random guess is as good as any other random guess. if you're an extreme "deliberator", then, as weird as it may sound, you may want to have an actual method for random guessing. this could be as simple as "pick the first one of the remaining choices", but anything you can do to prevent staring at the problem is good.

again, when you move through the above hierarchy, you need to progress EFFICIENTLY through the different steps. in other words, if one of the steps isn't working for you, you should more or less IMMEDIATELY move on to the next step. i like to follow a "10 second rule": if you stare at a problem for 10 seconds without doing anything, then it's time to move on to the next step of the hierarchy.
this may be difficult to implement at first, especially if you're a "deliberator" by nature, but it's ABSOLUTELY ESSENTIAL for your success on this exam. you will not be able to finish the quant section on time if you aren't adaptable and don't move quickly from one method of problem solving to another.

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- if you are wasting time DELIBERATING between two or three final choices, YOU MUST LEARN TO STOP DELIBERATING. you should get into a mental state where you can just make a decision, even if that decision is random.
if you're an extreme "deliberator" type - common in business school - then you may even want to figure out a systematic way to make random guesses! for instance, you might plan to always guess on the first remaining choice (say, (b) if you're down to (b) and (e)). whatever it takes so that you NEVER feel like staring at a problem.

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if you adopt this sort of STRICT hierarchical mentality, you will almost certainly do much better on the quant section. it's a difficult thing at first, because it's almost certainly alien to your current manner of thinking, but it will make a HUGE difference.