SAT Subject Math Level 2 Facts & Formulas
Numbers, Sequences, Factors
Integers:
. . .
, -3, -2, -1, 0, 1, 2, 3,
. . .
Reals:
integers plus fractions, decimals, and irrationals (
√
2,
√
3,
π
, etc.)
Order Of Operations:
PEMDAS
(Parentheses / Exponents / Multiply / Divide / Add / Subtract)
Arithmetic Sequences:
each term is equal to the previous term plus
d
Sequence:
t
1
,
t
1
+
d
,
t
1
+ 2
d
,
. . .
The n
th
term is
t
n
=
t
1
+ (
n
−
1)
d
Number of integers from
i
n
to
i
m
=
i
m
−
i
n
+ 1
Sum of
n
terms
S
n
= (
n/
2)
·
(
t
1
+
t
n
)
Geometric Sequences:
each term is equal to the previous term times
r
Sequence:
t
1
,
t
1
·
r
,
t
1
·
r
2
,
. . .
The n
th
term is
t
n
=
t
1
·
r
n
−
1
Sum of
n
terms
S
n
=
t
1
·
(
r
n
−
1)
/
(
r
−
1)
Sum of infinite sequence (
r <
1) is
S
∞
=
t
1
/
(1
−
r
)
Prime Factorization:
break up a number into prime factors (2, 3, 5, 7, 11,
. . .
)
200 = 4
×
50 = 2
×
2
×
2
×
5
×
5
52 = 2
×
26 = 2
×
2
×
13
Greatest Common Factor:
multiply common prime factors
200 = 2
×
2
×
2
×
5
×
5
60 = 2
×
2
×
3
×
5
GCF(200
,
60) = 2
×
2
×
5 = 20
Least Common Multiple:
check multiples of the largest number
LCM(200
,
60): 200 (no), 400 (no), 600 (yes!)
Percentages:
use the following formula to find part, whole, or percent
part =
percent
100
×
whole
http://www.erikthered.com/tutor
pg. 1