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45 terms

GRE Math Tricks

Quick Facts for GRE 2010
STUDY
PLAY
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