GMAT Prep Flashcards
(193 cards)
1
Q
1/6 (decimal)
A
.167
2
Q
1/7 (decimal)
A
.143
3
Q
1/8 (decimal)
A
.125
4
Q
1/9 (decimal)
A
.111
5
Q
1/25 (decimal)
A
.04
6
Q
Prime numbers (1-10)
A
2, 3, 5, 7
7
Q
Prime numbers (11-20)
A
11, 13, 17, 19 (toad, dam, tack, tub)
8
Q
Prime numbers (21-30)
A
23, 29 (name, knob)
9
Q
Prime numbers (31-40)
A
31, 37 (moat, mug)
10
Q
Prime numbers (41-50)
A
41, 43, 47 (rat, ram, rake)
11
Q
Prime numbers (51-60)
A
53, 59 (lamb, leap)
12
Q
Prime numbers (61-70)
A
61, 67 (cheetah, jack)
13
Q
Prime numbers (71-80)
A
71, 73, 79 (cat, comb, cap)
14
Q
Prime numbers (81-90)
A
83, 89 (foam, VP)
15
Q
Prime numbers (91-100)
A
97 (book)
16
Q
Factorizations rules
A
- ….Dividend is even
- ….Sum of digits is multiple of 3
- ….Last two digits multiple of 4
- ….Last digit is 0 or 5
- ….Even number and sum of digits multiple of 3 (Mult of 2 and 3)
- ….Sum of digits is multiple of 9
- ..Ends in 0
- ..Last 2 digits divisible by 25
17
Q
Rate (volume) =
A
Quantity/Time (Q/T)
18
Q
Rate (velocity) =
A
Distance/Time (D/T)
19
Q
Quantity =
A
Rate * Time
20
Q
Distance =
A
Rate * Time
21
Q
Time =
A
Quantity/Rate OR Distance/Rate
22
Q
A/B + C/D =
A
AD + BC / BD
23
Q
Where do I begin?
1) Answers are all numbers
A
Work Backwards (Problem Solving)
24
Q
Where do I begin?
2) Variables
A
Make up numbers
25
Where do I begin?
| 3) Really Hard!
Wouldn't it be nice if (WIBNI)
| Make it easier
26
Where do I begin?
| 4) Figures
P. S. : Drawn to scale
D. S. : Not Drawn to scale
1) Draw (if no figure)
2) If P. S. and already drawn, eyeball it
27
0 is a multiple of...
all numbers
28
1 is/is not prime because...
NOT; only has 1 factor
29
0 is/is not prime because...
NOT; not divisible by self
30
% Change =
(new value - original value)/original value * 100
31
Dividend/divisor -
Quotient + Remainder/divisor
32
Dividend =
Quotient * Divisor + Remainder
33
12 x 2
24
34
12 x 3
36
35
12 x 4
48
36
12 x 5
60
37
12 x 6
72
38
12 x 7
84
39
12 x 8
96
40
12 x 9
108
41
12 x 10
120
42
12 x 11
132
43
12 x 12
144
44
12 x 13
156
45
12 x 14
168
46
12 x 15
180
47
13 x 2
26
48
13 x 3
39
49
13 x 4
52
50
13 x 5
65
51
13 x 6
78
52
13 x 7
91
53
13 x 8
104
54
13 x 9
117
55
13 x 10
130
56
13 x 11
143
57
13 x 12
156
58
13 x 13
169
59
13 x 14
182
60
13 x 15
195
61
14 x 2
28
62
14 x 3
42
63
14 x 4
56
64
14 x 5
70
65
14 x 6
84
66
14 x 7
98
67
14 x 8
112
68
14 x 9
126
69
14 x 10
140
70
14 x 11
154
71
14 x 12
168
72
14 x 13
182
73
14 x 14
196
74
14 x 15
210
75
15 x 2
30
76
15 x 3
45
77
15 x 4
60
78
15 x 5
75
79
15 x 6
90
80
15 x 7
105
81
15 x 8
120
82
15 x 9
135
83
15 x 10
150
84
15 x 11
165
85
15 x 12
180
86
15 x 13
195
87
15 x 14
210
88
15 x 15
225
89
16^2
256
90
20^2
400
91
25^2
625
92
50^2
2500
93
2^3
8
94
2^4
16
95
2^5
32
96
2^6
64
97
2^7
128
98
2^8
256
99
2^9
512
100
2^10
1024
101
3^3
27
102
4^3
64
103
5^3
125
104
6^3
216
105
7^3
343
106
8^3
512
107
9^3
729
108
10^3
1000
109
Prime Numbers Test
1) Eliminate 2x and 5x
2) Eliminate 3x
3) Eliminate 7x
4) Eliminate 11x
5) Eliminate 13x
6) Continue to nearest Sq Root
110
What has an odd number of factors?
Perfect Square (e.g., 49, 81, etc.)
111
What has exactly 3 factors?
Prime number squared (e.g., 4, 9, 25, 49)
112
Factors are divisors (true/false)
True
113
Factors are multiples (true/false)
False
114
Number of unique factors trick
Break down to prime factors, take the power that each prime factor appears to, add one to each and multiply together. (ex. 100 = 2*2*5*5 = 2^2 * 5^2... (2+1)(2+1) = 9 unique factors)
115
Price - Discount =
Cost + Profit
116
Define: even integer
Any integer that when divided by 2 results in another integer
117
Define: odd integer
Any integer that when divided by 2 does not result in another integer
118
Define: Divisor (factor)
For an integer, a divisor is a positive integer that evenly divides into it
119
Define: multiple
Any integer that results from multiplying an integer with another integer
120
Because a multiple of N is N * any integer, multiples are:
infinite
121
Because only so many integers divide into N, factors are:
finite
122
O is a multiple of:
ALL numbers, because 0 times anything is 0, another integer
123
To find LCM (LCD of fractions):
1) Determine prime factors
2) Take each unique one to the highest power that it appears
3) Multiply them together
124
To find greatest common factor (GCF):
Find all prime factors then find common sets between all #s.
125
If you divide a smaller integer by a larger integer, the quotient is always ____ and the remainder is the ______
Zero; Dividend
126
Primes can/cannot be negative integers?
Cannot
127
Prime Factors of: 12
2^2 * 3
128
Prime Factors of: 24
2^3 * 3
129
Prime Factors of: 48
2^4 * 3
130
Prime Factors of: 56
2^3 * 7
131
Prime Factors of: 72
2^3 * 3^2
132
Prime Factors of: 140
2^2 * 5 * 7
133
Prime Factors of: 144
2^4 * 3^2
134
Odd +/- Odd =
Even
135
Odd * Odd =
Odd
136
Odd +/- Even =
Odd
137
Odd * Even =
Even
138
Even +/- Even =
Even
139
Even * Even =
Even
140
3^4 =
81 (9^2)
141
4^4 =
256 (16^2)
142
5^4 =
625 (25^2)
143
(a+b)^2 =
a^2 + 2ab + b^2
144
(a-b)^2 =
a^2 - 2ab + b^2
145
(x+y)(x-y) =
x^2 - y^2
146
x^2 - y^2 =
(x+y)(x-y)
147
Up one/Down one Rule for D. S.
D (Each)
A B (1, 2)
C (Together)
E (Neither)
148
Verbal:
Either X or Y
Neither X nor Y
which dictates singular/plural agreement
Y Dictates
149
Venn Diagram Formula
Total = Set X + Set Y - Both + Neither
150
Work =
Rate * Time
151
If work amount is 1 job, rate is:
Inverse of time (ex. 1 job = Rate * 5 hours
R = 1/5 job per hour
Rates are additive, Times are NOT. Always convert times to rates
152
Avg Speed =
Total Distance / Total Time
153
Triangle Area =
1/2 b * h
154
Longest triangle side is always opposite
largest angle (but lengths and angles are NOT necessarily proportional)
155
Right Triangles:
| Pythagorean Theorem
a^2 + b^2 = c^2
156
Common Right Triangle side lengths
3 - 4 - 5
5 - 12 - 13
1 - 1 - Root 2 (45 - 45 - 90)
1 - Root 3 - 2 (30 - 60 - 90)
157
Area of Equilateral Triangle
All sides equal, all angles 60 degrees, is isosceles
A = 1/4 S^2 Root 3
158
Central Angle/360 =
Minor Arc / Circumference
159
Pi =
Circumfrence / Diameter = 3.14 = 22/7
160
Circle Area =
Pi * R^2
161
Circle Circumference =
Pi * D = 2 Pi * r
162
Inscribed angle =
1/2 * Central angle to same points
163
Inscribed angle to end points of diameter =
90 degrees
164
Coordinate Geometry
| y =
mx + b
m is slope
b is y-intercept (where x=0)
165
Coordinate Geometry
| m =
Y2 - Y1 / X2 - X1
166
Coordinate Geometry
| Midpoint on line
(X1 + X2 / 2, Y1 + Y2 / 2)
167
Coordinate Geometry
| X-intercept
-b/m
| where Y = O
168
Perpendicular lines have slopes that are:
negative reciprocals (ex. 2, -1/2)
169
y = x^2 looks like
U
170
y = -x^2 looks like
n
171
x = y^2 looks like
c
172
x = -y^2 looks like
D
173
Circle equation:
x^2 + y^2 = k
174
mean = Avg =
sum of terms / number of terms
175
median =
middle value of ordered set (if even # of terms, avg two middle terms)
176
Mode =
Most frequently occurring value in set (can be multiple)
177
Range =
Difference between smallest and largest value (Always greater than or equal to 0)
178
Standard Deviation =
Measure of dispersion around the mean
179
If numbers in a set are evenly spaced, then:
mean = median and mean can be found by averaging highest and lowest values
180
Permutations / Combinatorics
N = # of items to arrange
K = # of spots to arrange them
Number of permutations (order matters) = nPk =
N! / (N - K)!
| Note: if N = K, denominator is 0! = 1, so answer is N!
181
0! =
1
182
Permutations / Combinatorics
N = # of items to arrange
K = # of spots to arrange them
Number of combinations (unordered) = nCk =
N! / K! (N-K)!
or
nPk / K!
183
Probability is between:
0 and 1, inclusive
184
Probability of "at least one" is:
P (at least 1) + P (none) = 1
185
1! =
1
186
2! =
2
187
3! =
6
188
4! =
24
189
5! =
120
190
6! =
720
191
Arithmetic Shortcuts:
| Divide by 5
Double and divide by 10 (move decimal to left by 1)
192
Arithmetic Shortcuts:
| To square a number ending in 5
Multiply tens digit by (that digit + 1), then tack 25 to end of that number (ex. 45^2 = 4*5 = 2025
193
Arithmetic Shortcuts:
| A*B =
(2A)(1/2B)
| Double one and half the other, then multiply
