GRE MATH Flashcards
1
Q
Percent increase /decrease
A
amount increase/decrease over original whole
2
Q
multiple of 3
A
sum of digits is multiple of 3
3
Q
multiple of 4
A
last two digits are multiple of four
4
Q
multiple of 6
A
last two digits are multiple of 3 and its even
5
Q
multiple of nine
A
sum of digits is multiple of 9
6
Q
(a+b)2
A
a2 +2ab+b2
7
Q
(a-b)2
A
a2-2ab+b2
8
Q
a2 - b2
A
(a+b)(a-b)
9
Q
Specific special right triangles
A
3,4,5 and 5,12,13
10
Q
special right triangels
A
1:sqrt3:2 and 1:1:sqrt 2
11
Q
simple interest
A
interest = principal x interest rate x time
12
Q
combined work problems
A
1/r +1/s = 1/t
r,s = number of hours to do job
t - time
13
Q
permutation
A
order matters
n!/ (N-c)!
14
Q
combination
A
order doesnt matter
n!/c!(n-c)!
15
Q
volume cylinder
A
pir2 h
