GRE Math Flashcards
1
Q
Percentage Change Formula
A
(Difference/Original) X 100
2
Q
Standard Deviation Percents
A
From the center, 1 SD = 34% or 68%, 2 SD = 14% or 96%
3
Q
Third Side Rule
A
The length of any one side of a triangle must be less than the sum of the other two sides and greater than the difference between the other two sides
4
Q
Height of an equilateral triangle
A
Xsqrt(3) where X = half of the base
5
Q
Hypotenuse of a right isosceles (diagonal of a square)
A
Xsqrt(2) where X = the length of the other sides
6
Q
Diagonal in a three dimensional box
A
A^2+B^2+C^2=D^2
7
Q
A is X% of B
A
A = XB/100
8
Q
Even+Even
A
Even
9
Q
Odd+Odd
A
Even
10
Q
Even+Odd
A
Odd
11
Q
Even X Even
A
Even
12
Q
Odd X Odd
A
Odd
13
Q
Even X Odd
A
Even
14
Q
Prime Numbers
A
2, 3, 5, 7, 11, 13, 17, 19, 23, 29 (no negative primes)
15
Q
Divisible by 3
A
Its digits add up to a multiple of 3
