SAT Math · Study & Practice
Percentages
Percentages turn up in a huge share of SAT word problems — discounts, taxes, tips, growth and data interpretation all rely on them. This chapter covers the percentage concept, increase and decrease, successive percentages, discounts, markups, sales tax and tips/commissions. Read each topic, try the problems with the hint ladder, then take the 8-question topic test.
Topics
1
Percentage Concepts
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2
Percentage Increase
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3
Percentage Decrease
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4
Successive Percentages
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5
Discounts
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6
Markups
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7
Sales Tax
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8
Tips and Commissions
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Chapter test
Formula Reference Sheet
This chapter
Core percentage
| Percent of a number | P% of N = (P/100) × N |
|---|---|
| What percent | part ÷ whole × 100% |
| Find the whole | whole = part ÷ (P/100) |
| Decimal of P% | P% = P/100 |
Change & money
| Percent change | (change ÷ original) × 100% |
|---|---|
| Increase by P% | × (1 + P/100) |
| Decrease by P% | × (1 − P/100) |
| Successive changes | multiply the factors |
| Final price w/ tax | price × (1 + tax%) |
Digital SAT reference
Area & Circumference
| Circle area | A = πr² |
|---|---|
| Circle circumference | C = 2πr |
| Rectangle | A = ℓw |
| Triangle | A = ½ b h |
Volume
| Rectangular box | V = ℓwh |
|---|---|
| Cylinder | V = πr²h |
| Sphere | V = 4⁄3 πr³ |
| Cone | V = 1⁄3 πr²h |
| Pyramid | V = 1⁄3 ℓwh |
Right triangles
| Pythagorean theorem | a² + b² = c² |
|---|---|
| 30°–60°–90° | sides x : x√3 : 2x |
| 45°–45°–90° | sides s : s : s√2 |
Constants
| Degrees in a circle | 360° |
|---|---|
| Radians in a circle | 2π |
| Angles of a triangle | sum = 180° |
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