GRE Numbers Flashcards
(201 cards)
1
Q
Prime numbers less than 30
A
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
2
Q
An integer is divisible by 2 if…
A
…its units digit is divisible by 2.
3
Q
An integer is divisible by 3 if…
A
…the sum of its digits are divisible by 3.
4
Q
An integer is divisible by 4 if…
A
…its last two digits form a number that’s divisible by 4. Thus, 712 is div. by 4 b/c 12 is div. by 4.
5
Q
An integer is divisible by 5 if…
A
…its units digit is either 0 or 5.
6
Q
An integer is divisible by 6 if…
A
…it is divisible by both 2 and 3.
7
Q
An integer is divisible by 9 if…
A
…the sum of its digits is divisible by 9.
8
Q
An integer is divisible by 10 if…
A
…its units digit is 0.
9
Q
Quotient
A
the result of division
10
Q
Divisor
A
the number you divide by
11
Q
Numerator
A
the top number in a fraction
12
Q
denominator
A
the bottom number in a fraction
13
Q
Order of operations in solving a complex problem
A
PEMDAS (Please Excuse My Dear Aunt Sally): 1. parentheses 2. exponents 3. multiplication/division 4. addition/subtraction
14
Q
1/100 = .? = ?%
A
0.01 = 1%
15
Q
1/10 = .? = ?%
A
0.1 = 10%
16
Q
1/5 = .? = ?%
A
0.2 = 20%
17
Q
1/4 = .? = ?%
A
0.25 = 25%
18
Q
1/3 = .? = ?%
A
0.333 = 33 1/3%
19
Q
2/5 = .? = ?%
A
0.4 = 40%
20
Q
1/2 = .? = ?%
A
0.5 = 50%
21
Q
3/5 = .? = ?%
A
0.6 = 60%
22
Q
2/3 = .? = ?%
A
0.666 = 66 2/3%
23
Q
4/5 = .? = ?%
A
0.8 = 80%
24
Q
3/4 = .? = ?%
A
0.75 = 75%
25
1/1 = ? = ?%
1.0 = 100%
26
2/1 = ? = ?%
2.0 = 200%
27
√2 =
1.4
28
√3 =
1.7
29
√4 =
2
30
Median
the middle value in a set of numbers
31
Mode
is the number or range of numbers in a set that occurs the most frequently: Mode = most
32
Range
is the difference between the highest and the lowest numbers in your set
33
The rates of normal distribution on a bell curve?
is 34:14:2
34
Factored form: x2 - y2
Unfactored form: (x+y)(x-y)
35
Factored form: (x+y)2
Unfactored form: x2 + 2xy + y2
36
Factored form: (x-y)2
Unfactored form: x2 - 2xy + y2
37
FOIL stands for…
first, outer, inner, last
38
To solve a permutation…
figure out how many slots you have, write down the number of options for each slot, and multiply them. Ex. 5X4x3 = 60
39
To solve a combination…
figure out how many slots you have, fill in the slots as you would a permutation, and then divide by the factorial of the number of slots.
40
Factorial: 6!
A factorial of a number is equal to that number times every positive whole number smaller than itself, down to 1: 6x5x4x3x2x1 = 720
41
Equation for finding probability
42
Average formula as pie chart
43
Rate formula
d=rt
avg speed = total distance ÷ time
44
Formula for percent change
Definition of terms: if you need to find the % increase, the "original" # will be the lower #. If you need to find the % decrease, the "original" # will be the higher #.
45
Line equation
y = mx + b
46
Slope equation
rise/run
47
Perimeter of a rectangle
the sum of the lengths of its four sides
48
Area of a rectangle
is the length times its width (lxW)
49
Diagonal of a square =
is 45:45:90
50
Perimeter of a square
four times the amount of one side
51
Each angle of an equilateral triangle =
60 degrees
52
Isosceles triangle
two of the three sides are equal in length
53
The longest side of a right triangle is called
the hypotenuse
54
Perimeter of a triangle
the sum of the lengths of the sides
55
the third-side rule
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
56
Area of a triangle
A = 1/2bh
57
Pythagorean theorem
only applies to right triangles
58
What are the three pythagorean triples?
3-4-5; 6-8-10; 5-12-13
59
What are the angles and the sides of a Isosceles right triangle?
angles: 45:45:90 sides: x:x:x√2
60
What are the sides of a 30:60:90 right triangle?
x:x√3:2x
61
Area of a square
any side squared
62
Formula for volume of a rectangular solid
lwh (length x width x height or depth)
63
Volume of a cylinder
πr²h
64
In y=mx+b, x and y stand for
points on the line
65
In y=mx+b, b stands for
y-intercept, or the point at which the line crosses the y-axis
66
In y=mx+b, m stands for
the slope of the line
67
The formula to find the length of a diagonal inside a three dimensional box
a2 + b2 + c2 = d2
68
The surface area of a rectangular box is equal to
the sum of the areas of all of its sides. Ex., a box whose dimensions are 2x3x4. Two sides of 2x3, two sides of 3x4, and two sides of 2x4. Thus, 6+6+12+12+8+8=52=surface area
69
Formula to find the radius of an area 49π
√49
70
The three types of assumptions for an argument essay. What are they and what are the keys to identifying them?
1. Sampling Assumption: Look for a conclusion that generalizes from a small sample of evidence (e.g., 2 out of 5 dentists recommend….) 2. Analogy Assumption: assumes that the items being compared are the same. 3. Causal Assumption: these always assume that (1) if you remove the cause, you will remove the effect and (2) there is no other cause. Look for words like "causes," "responsible for," and "due to."
71
⅛ = .? = ?%
0.125 = 12.5%
72
⅜ = .? = ?%
0.375 = 37.5%
73
⅝ = .? = ?%
0.625 = 62.5%
74
⅞ = .? = ?%
0.875 = 87.5%
75
Perimeter of a rectangle
sum of the lengths of its four sides
76
Area of a rectangle
l x w
77
Perimeter of a square
4 times the length of any side
78
The sum of the three angles of any triangle
180º
79
An equilateral triangle has…
three sides equal in length and three equal angles
80
The angles of an equilateral triangle are
60º each
81
The angles of a right triangle are…
30º 60º 90º
82
An isosceles triangle is a triangle in which…
two of the three sides and two of the three angles are equal
83
Perimeter of a triangle
the sum of the sides
84
MA/DS/PM
multiply -\> add / divide -\> subtract / power -\> multiply
85
The result of any non-zero number to the 0 power
1
86
A negative exponent means
"one over" (and make it positive), or the reciprocal
87
A negative number to an even power…
becomes positive
88
A negative number to an odd power…
stays negative
89
1 to any power…
remains 1
90
0 to any power…
remains 0
91
When taken to a higher power a fraction between 0 and 1 always gets…
smaller
92
23
8
93
24
16
94
33
27
95
34
81
96
43
64
97
44
256
98
53
125
99
√121
11
100
√144
12
101
√169
13
102
√196
14
103
√225
15
104
√256
16
105
√625
25
106
3√8
2
107
3√27
3
108
3√64
4
109
3√125
5
110
3√216
6
111
taking the root of a number between 0 and 1 makes the number…
larger
112
√1 =
1
113
100% or 1.0 as fraction
1/1
114
87.5% or .875 as fraction
⅞
115
80% or .8 as fraction
4/5
116
75% or .75 as fraction
¾
117
62.5% or .625 as fraction
⅝
118
60% or .6 as fraction
3/5
119
66 ⅔ % or .666 as fraction
⅔
120
37.5% or .375 as fraction
⅜
121
40% or .4 as fraction
2/5
122
25% or .25 as fraction
¼
123
20% or .2 as fraction
1/5
124
12.5% or .125 as fraction
⅛
125
33 ⅓ % or .333 as fraction
⅓
126
132
169
127
142
196
128
152
225
129
162
256
130
252
625
131
63
216
132
PRICE stands for (purpose, or why)
Predict, Recommend, Inform, Correct, Evaluate
133
Different type of "structures" for reading comp. (how)
Cause/Effect (C/E), Chronology (Ch), Classification (Cl), Comparison/Contrast (C/C), Steps/Stages (S)
134
r d C A =
radius, diameter, circumference, area
135
3√5 + 4√5 =
7√5
136
√3 x √12 =
√36 = 6
137
3√2 x 4√5 =
12√10
138
(√3)² =
√9 = 3
139
√2x2x2x2x5 =
2x2√5 = 4√5 Rule: two of something on the inside of the radical is equal to one of the same on the outside of the radical
140
Formula to find an arc of a circle
angle/360º = arc/circumference
141
Formula to find the sector of a circle
angle/360º = sector/area
142
9 + 5 =
14
143
9 + 4 =
13
144
9 + 3 =
12
145
9 + 6 =
15
146
8 + 4 =
12
147
8 + 5 =
13
148
14 - 9 =
5
149
14 - 5 =
9
150
13 - 9 =
4
151
13 - 4 =
9
152
12 - 9 =
3
153
12 - 3 =
9
154
12 - 8 =
4
155
13 - 8 =
5
156
13 - 5 =
8
157
7 + 5 =
12
158
12 - 7 =
5
159
12 - 5 =
7
160
7 + 4 =
11
161
11 - 7 =
4
162
11 - 4 =
7
163
0.01 = 1%
1/100 = .? = ?%
164
0.1 = 10%
1/10 = .? = ?%
165
0.2 = 20%
1/5 = .? = ?%
166
0.25 = 25%
1/4 = .? = ?%
167
0.333 = 33 1/3%
1/3 = .? = ?%
168
0.4 = 40%
2/5 = .? = ?%
169
0.5 = 50%
1/2 = .? = ?%
170
0.6 = 60%
3/5 = .? = ?%
171
0.666 = 66 2/3%
2/3 = .? = ?%
172
0.8 = 80%
4/5 = .? = ?%
173
0.75 = 75%
3/4 = .? = ?%
174
1.0 = 100%
1/1 = ? = ?%
175
2.0 = 200%
2/1 = ? = ?%
176
Unfactored form: (x+y)(x-y)
Factored form: x2 - y2
177
Unfactored form: x2 + 2xy + y2
Factored form: (x+y)2
178
Unfactored form: x2 - 2xy + y2
Factored form: (x-y)2
179
0.125 = 12.5%
⅛ = .? = ?%
180
0.375 = 37.5%
⅜ = .? = ?%
181
0.625 = 62.5%
⅝ = .? = ?%
182
0.875 = 87.5%
⅞ = .? = ?%
183
1/1
100% or 1.0 as fraction
184
⅞
87.5% or .875 as fraction
185
4/5
80% or .8 as fraction
186
¾
75% or .75 as fraction
187
⅝
62.5% or .625 as fraction
188
3/5
60% or .6 as fraction
189
⅔
66 ⅔ % or .666 as fraction
190
⅜
37.5% or .375 as fraction
191
2/5
40% or .4 as fraction
192
¼
25% or .25 as fraction
193
1/5
20% or .2 as fraction
194
⅛
12.5% or .125 as fraction
195
⅓
33 ⅓ % or .333 as fraction
196
Probability of events A + B
A x B
197
Probabilty of A or B
A + B
198
Probability of "at least once"
1 - probability of never
199
Probability of events A + B
A x B
200
Probabilty of A or B
A + B
201
Probability of "at least once"
1 - probability of never
