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