### Bookshelf

 Total GMAT Math Jeff's complete Quant guide, on sale now!
 Total GMAT Verbal Everything you need to ace GMAT Verbal!
 New: GMAT 111 Improve every aspect of your GMAT prep!

1,800 Practice Math Questions

GMAT Official Guide
OG Math | OG Verbal

Guides To the Official Guide
Free: OG12 explanations!

GMAT Question of the Day

Beginner's Guide to the GMAT

GMAT Hacks Affiliate Program

### Resources

MBA.com
GMAC Official Site
Free GMATPrep Practice Tests

Stacy Blackman Consulting
Book | Essay Guides

GRE HQ
Total GRE Math

Ultimate SAT Verbal

## Official Guide Explanations:Questions by Content Area

Background

This directory links you to hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Review (12th ed.). There are lists of explanations sorted by question number, difficulty level, and content area. Question numbers beginning with a 'D' are from the book's Diagnostic Test.

I've also created explanations for the problems in the 2nd edition of the Official Guide for Quantitative Review.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

Algebra > Absolute Value
PS
22, 50, 130
DS
1, 69, 153

Algebra > Equations
PS
4, 6, 26, 31, 34, 74, 77, 84, 115, 120, 127, 150, 163, 176, 188, 202, 213, D16, D24
DS
26, 138, 150, D35, D37

Algebra > Exponents
PS
104, 112, 133, 164, 171, 228, 230, D16
DS
30, 36, 97, 151, 153, 154, 156, 165, 166, D33, D44

Algebra > Functions
PS
58, 68, 81, 85, 146, 157, 171, 228, D03
DS
19, 26, 36, 45, 115

Algebra > Inequalities
PS
49, 71, 104, 119, 125, 130, 173, 229
DS
11, 49, 51, 69, 72, 79, 80, 97, 121, 146, 156, 159, 162, 166, D32, D37, D38, D41

Algebra > Linear Equations-One Unknown
PS
2, 18, 38, 44, 53, 57, 59, 62, 65, 68, 70, 83, 88, 100, 103, 116, 132, 144, 155, 168, 172, 176, 184, 187, 206, 207, 215, 218, 222, 226
DS
13, 39

Algebra > Linear Equations-Two Unknowns
PS
58, 70, 90, 91, 134, 140, 153, 165, 180, 196, 211, 227, D12, D24
DS
8, 15, 30, 33, 35, 54, 56, 60, 62, 71, 72, 84, 88, 95, 99, 108, 123, 131, 137, 145, 148, 152, 157

Algebra > Simplifying Algebraic Expressions
PS
45, 79, 112, 117, 119, 148, 202, 208, 215, 230, D01
DS
53, 83, 168, D35

Algebra > Solving Equations by Factoring
PS
41, 97
DS
None

PS
41, 97, 144, 227
DS
None

Algebra > Symbolism
PS
42, 122, 136, 143, 188
DS
100, 115, 125

Arithmetic > Counting Methods
PS
121, 135, 191, D11
DS
None

Arithmetic > Decimals
PS
15, 37, 38, 46, 56, 73, 79, 106, 108, 111, 114, 137, 139, 203, 226, D01
DS
31, 43, 46, 64, 139

Arithmetic > Descriptive Statistics
PS
5, 14, 27, 57, 69, 93, 99, 123, 132, 148, 180, 184, 199, 201, D02, D09
DS
28, 32, 53, 81, 84, 93, 105, 116, 129, 133, 134, 136, 141, 147, D31, D32, D43, D46

Arithmetic > Discrete Probability
PS
12, 67, 105, 158, 174, 214, D07
DS
3, 86, 107

Arithmetic > Fractions
PS
3, 10, 14, 20, 24, 29, 37, 43, 45, 46, 56, 74, 75, 89, 95, 113, 122, 126, 129, 138, 168, 175, 176, 181, 186, 187, 203, 208, 213, 214, 215, 216, 218, 222, 225, D08, D13
DS
27, 43, 46, 51, 59, 70, 90, 107, 108, 139, 150, 166, 168, D41

Arithmetic > Percents
PS
8, 10, 13, 17, 19, 47, 55, 60, 64, 78, 84, 92, 94, 105, 109, 111, 115, 123, 124, 131, 139, 149, 151, 156, 166, 183, 187, 200, 202, 220, 223, D04, D12, D21
DS
21, 33, 37, 48, 52, 55, 63, 77, 79, 88, 89, 92, 120, 129, 142, 143, D29, D34, D46

Arithmetic > Powers and Roots of Numbers
PS
11, 15, 32, 46, 51, 54, 73, 98, 104, 112, 114, 117, 133, 136, 137, 155, 161, 172, 216, 226, 230, D15, D16, D17
DS
1, 66, 151, 154, 156, 162, 164, 165, 169, 170, D25, D33, D44

Arithmetic > Properties of Integers
PS
3, 7, 12, 23, 35, 36, 40, 49, 72, 82, 87, 89, 106, 107, 110, 125, 142, 157, 159, 161, 182, 185, 190, 198, 201, 203, 211, 217, 219, 224, D13, D18, D23
DS
6, 12, 16, 17, 24, 31, 41, 46, 51, 53, 57, 65, 66, 73, 76, 82, 90, 93, 98, 100, 106, 110, 123, 128, 139, 167, 170, 171, 172, D25, D26, D42, D44

Arithmetic > Ratio and Proportion
PS
1, 6, 8, 20, 21, 52, 55, 61, 63, 66, 76, 80, 84, 86, 96, 103, 109, 118, 120, 131, 141, 154, 162, 169, 179, 192, 195, 204, 223
DS
9, 38, 39, 42, 48, 52, 58, 60, 61, 78, 80, 85, 87, 103, 111, 112, 114, 143, 150, 154, 155, 158, 163, 174

Arithmetic > Real Numbers
PS
29, 114, 150, 173, 182
DS
11, 41, 65, 95, 125, 159, 169, 171

Arithmetic > Sets
PS
124, 167, 170, 178, 193, 200, 221, D04, D06, D14
DS
2, 4, 21, 50, 67, 89, 92, 113, 124, 126, 127, D29, D34, D47

Geometry > Circles
PS
33, 160, 197, 212, D20
DS
42, 96, 114, 117, 160, 173, D36

Geometry > Coordinate Geometry
PS
9, 25, 30, 39, 88, 194, 205, 210, 212, 229
DS
75, 94, 121, 149, 164, D39

Geometry > Intersectings Lines and Angles
PS
53, 62, 194, 209
DS
132

Geometry > Lines
PS
48, 130
DS
5, 91, 108

Geometry > Perpendicular Lines
PS
194
DS
None

Geometry > Polygons (Convex)
PS
D10
DS
None

PS
4, 18, 62, 102, 113, 118, 134, 145, 177
DS
18, 132, 135, 144, 148, D48

Geometry > Rectangular Solids and Cylinders
PS
16, 177, 189, D05, D22
DS
18, 29, 34, 122

Geometry > Triangles
PS
48, 102, 145, 147, 152, 177, 205, 209, 229, D10, D19
DS
20, 56, 74, 109, 135, 140, 144, 149, 157, 160, 173, D28, D48

Word Problems > Data Interpretation
PS
5, 30, 69, 81, 116, 196
DS
40, 96

Word Problems > Discount
PS
64, 111, 115, 123, 151
DS
63

Word Problems > Geometry Problems
PS
16, 18, 26, 135, 147, 152, 160, 189, 197, D05, D22
DS
18, 34, 42, 114, 164

Word Problems > Interest Problems
PS
78, 128, D21
DS
7, 78, D40

Word Problems > Measurement Problems
PS
28, 63, 154
DS
14, 130

Word Problems > Mixture Problems
PS
14, 47, 61, 94, 132, 156, 166, 223
DS
59, 85, 101, 131, 141

Word Problems > Other
PS
17, 35, 59, 60, 72, 77, 87, 140, 141, 153, 155, 163, 165, 186, 217, 225, D08
DS
5, 9, 13, 22, 27, 28, 32, 37, 54, 55, 57, 58, 62, 70, 71, 77, 79, 86, 111, 116, 128, 138, 142, 143, 145, 155, 161, 163, 174, D27, D30, D45

Word Problems > Profit
PS
83
DS
23, 33, 52

Word Problems > Rate Problems
PS
1, 6, 8, 21, 31, 34, 47, 52, 55, 75, 76, 86, 96, 98, 103, 118, 127, 129, 131, 138, 149, 154, 162, 169, 175, 181, 183, 192, 195, 197, 204, 206, 207, 220, D24
DS
10, 14, 25, 44, 47, 61, 87, 102, 103, 104, 118, 146, 158, D38

Word Problems > Sets
PS
30, 105, 124, 158, 167, 170, 174, 178, 191, 193, 200, 214, 221, D04, D06, D14
DS
2, 4, 21, 50, 67, 89, 92, 113, 119, 124, 126, 127, 141, D29, D34, D47

Word Problems > Work Problems
PS
80, 101, 126, 204, 213
DS
44, 68, 112

 You should follow me on Twitter. While you're at it, take a moment to subscribe to GMAT Hacks via RSS or Email.

 Total GMAT Math The comprehensive guide to the GMAT Quant section. It's "far and away the best study material available," including over 300 realistic practice questions and more than 500 exercises! Click to read more.