GRE Math Tricks

Created by Davempeters 

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45 terms · Quick Facts for GRE 2010

even + even

even

even + odd

odd

odd + odd

even

even x even

even

even x odd

even

odd x odd

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

2 cubed

8

2 to the 4th

16

2 to the 5th

32

2 to the 6th

64

3 cubed

27

3 to the 4th

81

4 cubed

64

5 cubed

125

11 squared

121

13 squared

169

14 squared

196

15 squared

225

16 squared

256

20 squared

400

25 squared

625

square root of 2

1.4

square root of 3

1.7

square root of 5

2.2

Associative Property

(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

Area of a rectangle

A=lw

Perimeter of a rectangle

P=2l+2w

Area of a circle

A=pi(r^2)

Circumference

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

Length of an arc

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

pi

3.14 or 22/7

Volume

V=lwh

Surface area

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

Flickr Creative Commons Images

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