# GRE Math Tricks

### 45 terms by Davempeters

#### Study  only

Flashcards Flashcards

Scatter Scatter

Scatter Scatter

## Create a new folder

Quick Facts for GRE 2010

even

odd

even

even

even

odd

### prime numbers

2, 3, 5, 7, 11, 13, 17, 19 , 23, 29, 31, 37, 39, 41, 43, 47...

### LCD - lowest common denominator

Cross out any prime factor in the second denominator that already appears in the first denominator. then multiply the rest.

### Average

sum of all the numbers in the set divided by the number of elements in the set.

### Median

the middle value in a set containing odd numbers; a set with even numbers it is the average of the two middle terms.

### Mode

the value that appears the most often in the set

8

16

32

64

27

81

64

125

121

169

196

225

256

400

625

1.4

1.7

2.2

(a+b)+c=a+(b+c)

### distributive property

ab+ac=a(b+c) OR ab-ac=a(b-c)

### Differences of Squares

a^2 - b^2 = (a+b) (a-b)

### Fractions or decimals less than 1 raised to a power

will result in a number smaller than the original number

### supplementary angles

two angles that form a straight line

### acute angle

angle is greater than 0 but less than 90 degrees

### complementary angles

two angles form a 90 degree angle

### vertical angles

Happens when two lines intersect, vertical angles are equal

A=lw

P=2l+2w

A=pi(r^2)

### Circumference

C=pi(d) or 2(pi)r

### Length of an arc

Arc=(x/360)x2(pi)r

3.14 or 22/7

V=lwh

### Surface area

S=6a^2: sum of the areas of all faces

Example: