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Flashcards in GMAT: Quant Deck (19):
1

If question stem or ACs involve an inequality, you must...

Solve through. Inequals give you RANGES, not definitive answers. You have to calculate to see if things work out (can't just use logic).

2

Question about medians or standard deviation - do you have to solve through?

No - the GMAT tests conceptual understanding on these probs.

3

If two numbers share a factor, their sum or difference will...

...also share that factor.

4

What is the purpose of large factorials?

Just to convey a huge #. Pay closer attn to how other numbers interrelate with that #.

5

Data Sufficiency prob asks about the units digit of a #, or an answer...

...you MUST write out the first 5 or 6 possibilities and look for a pattern.

6

If the question has 3 variables and you come up with 3 separate equations (from q. stem and ACs), need you continue solving?

No - if the # of diff. equations matches the # of variables your solving for, you're done.

7

The product of k consecutive integers is divisible by...

k! (k factorial)

8

For any set of consecutive int w/an ODD # of items, the sum is always...*What about an EVEN #?

...a MULTIPLE of the # of items.*NEVER a multiple of the # of items.

9

Combinatorics: 2 key considerations

1) Is it an AND (i.e. multiply) or OR (i.e. add) problem,2) Remember to divide by both the # involved/include AND the # excluded: 2!2!

10

Multiplying by powers of 10

Positive powers of 10:-Multiply = right-Divide = leftNegative powers of 10:-Multiply = right-Divide = left

11

Fractions: ADD the same value to numerator and denominator... (subtract?)

...get closer to 1.(SUBTRACT = closer to 0)

12

Comparing fractions technique?

Cross-multiply

13

Fractions: MULTIPLY the numerator and denom. by the same value?

No change.

14

Fractions: MULTIPLY pos, proper fraction by a pos, proper fraction?

Closer to zero.

15

The sum if any two primes will be..

...even (odd + odd = even)

16

Fractions: DIVIDE pos, proper fraction by a pos, proper fraction?

Closer to 1.

17

If you see an inequality w/a zero on one side, consider testing...

...pos/neg scenarios.

18

Sets: good "sample sets"" for non-consec sets"

5: 2 4 5 6 8

19

Test fractions for a fraction-over-a-fraction: e.g. c/d (and both are fractions)

1/5 / 1/2 = 2/5 (i.e. still a fraction)