Why a GED Math Formula Cheat Sheet Matters
The GED Mathematical Reasoning test is one of the four subject tests you must pass to earn your GED credential. It covers 46 questions in 115 minutes and requires you to work with algebra, geometry, data analysis, and basic statistics. The good news? The GED Testing Service provides an official formula sheet during the exam. The bad news? If you don’t understand how to use those formulas, having them on paper won’t help much.
This cheat sheet breaks down every formula you’re likely to encounter on the GED math test, organized by category, with clear explanations and practical examples. Whether you’re weeks away from testing or just starting your study plan, mastering these formulas will give you a significant advantage on test day.
The Official GED Formula Sheet
During the GED math test, you will have access to an on-screen formula sheet. According to the GED Testing Service, this sheet includes formulas for area, perimeter, surface area, volume, and coordinate geometry. However, it does not include everything you need to know — basic algebraic rules, order of operations, and statistical calculations are expected from memory.
Understanding what is and isn’t on the formula sheet is the first step in smart test preparation. Focus your memorization energy on the formulas that aren’t provided, and focus your comprehension energy on the ones that are.
Geometry: Area and Perimeter Formulas
Geometry questions make up a significant portion of the GED math test. These formulas will be on your provided formula sheet, but you should understand them thoroughly.
Rectangle and Square
- Area of a Rectangle: A = l × w (length times width)
- Perimeter of a Rectangle: P = 2l + 2w
- Area of a Square: A = s² (side squared)
- Perimeter of a Square: P = 4s
Example: A rectangular garden measures 12 feet by 8 feet. Its area is 12 × 8 = 96 square feet. Its perimeter is 2(12) + 2(8) = 40 feet.
Triangle
- Area of a Triangle: A = ½bh (one-half base times height)
- Pythagorean Theorem: a² + b² = c² (for right triangles, where c is the hypotenuse)
Example: A triangle with a base of 10 inches and a height of 6 inches has an area of ½(10)(6) = 30 square inches.
Circle
- Area of a Circle: A = πr² (pi times radius squared)
- Circumference of a Circle: C = 2πr or C = πd (pi times diameter)
Example: A circle with a radius of 5 cm has an area of π(5²) = 25π ≈ 78.54 square centimeters. Its circumference is 2π(5) = 10π ≈ 31.42 cm.
Trapezoid
- Area of a Trapezoid: A = ½(b₁ + b₂)h (one-half the sum of the two bases times height)
Parallelogram
- Area of a Parallelogram: A = bh (base times height — note the height is perpendicular to the base, not the slant side)
Geometry: Volume and Surface Area Formulas
Three-dimensional geometry questions are common on the GED. These formulas are provided on the formula sheet.
Rectangular Prism (Box)
- Volume: V = lwh (length × width × height)
- Surface Area: SA = 2lw + 2lh + 2wh
Example: A storage box that is 4 feet long, 3 feet wide, and 2 feet tall has a volume of 4 × 3 × 2 = 24 cubic feet.
Cylinder
- Volume: V = πr²h (pi times radius squared times height)
- Surface Area: SA = 2πr² + 2πrh
Example: A cylindrical water tank with a radius of 3 meters and a height of 10 meters holds π(3²)(10) = 90π ≈ 282.74 cubic meters of water.
Cone
- Volume: V = ⅓πr²h
Sphere
- Volume: V = ⁴⁄₃πr³
- Surface Area: SA = 4πr²
Pyramid
- Volume: V = ⅓Bh (where B is the area of the base)
Algebra: Essential Equations
Algebraic problem solving accounts for approximately 55% of the GED math test. While the formula sheet covers some of these, you should have a strong working knowledge of all of them.
Linear Equations
- Slope-Intercept Form: y = mx + b (where m is the slope and b is the y-intercept)
- Slope Formula: m = (y₂ - y₁) / (x₂ - x₁)
- Point-Slope Form: y - y₁ = m(x - x₁)
- Standard Form: Ax + By = C
Example: Find the slope of the line passing through points (2, 5) and (6, 13). Using the slope formula: m = (13 - 5) / (6 - 2) = 8/4 = 2. The slope is 2, meaning y increases by 2 for every 1-unit increase in x.
Quadratic Equations
- Standard Form: ax² + bx + c = 0
- Quadratic Formula: x = (-b ± √(b² - 4ac)) / 2a
Example: Solve x² + 5x + 6 = 0. Here a = 1, b = 5, c = 6. Using the quadratic formula: x = (-5 ± √(25 - 24)) / 2 = (-5 ± 1) / 2. So x = -2 or x = -3.
Distance and Midpoint
- Distance Formula: d = √((x₂ - x₁)² + (y₂ - y₁)²)
- Midpoint Formula: M = ((x₁ + x₂)/2, (y₁ + y₂)/2)
Exponent Rules
These are not on the formula sheet and must be memorized:
- x^a × x^b = x^(a+b)
- x^a / x^b = x^(a-b)
- (x^a)^b = x^(ab)
- x^0 = 1
Statistics and Data Analysis
The GED math test includes questions about central tendency, data interpretation, and basic probability. These formulas are generally not on the provided formula sheet.
Measures of Central Tendency
- Mean (Average): Add all values together and divide by the number of values. Mean = (sum of all values) / n
- Median: The middle value when all numbers are arranged in order. For an even count, average the two middle values.
- Mode: The value that appears most frequently in a data set. A set can have no mode, one mode, or multiple modes.
- Range: The difference between the highest and lowest values. Range = maximum - minimum.
Example: For the data set {4, 7, 7, 9, 13}: Mean = (4 + 7 + 7 + 9 + 13) / 5 = 40/5 = 8. Median = 7 (the middle value). Mode = 7 (appears twice). Range = 13 - 4 = 9.
Weighted Mean
When values have different weights or frequencies: Weighted Mean = Σ(value × weight) / Σ(weights)
Probability Basics
- Simple Probability: P(event) = Number of favorable outcomes / Total number of possible outcomes
- Probability of Two Independent Events: P(A and B) = P(A) × P(B)
- Complementary Probability: P(not A) = 1 - P(A)
Example: A bag contains 3 red marbles, 5 blue marbles, and 2 green marbles. The probability of drawing a blue marble is 5/10 = 1/2 = 0.5 or 50%.
Percentages, Ratios, and Proportions
These concepts appear frequently on the GED and are not covered by the formula sheet.
- Percent: Part / Whole × 100
- Percent Change: ((New Value - Old Value) / Old Value) × 100
- Proportion: a/b = c/d (cross-multiply to solve: ad = bc)
- Simple Interest: I = Prt (Principal × rate × time)
- Compound Interest: A = P(1 + r/n)^(nt)
Example: If a shirt originally costs $40 and is on sale for $30, the percent change is ((30 - 40) / 40) × 100 = -25%. That’s a 25% discount.
Study Tips for GED Math Success
Practice with the formula sheet. Download the official GED formula sheet from ged.com and use it during practice sessions so you’re comfortable finding formulas quickly on test day.
Focus on word problems. According to the GED Testing Service, most math questions are presented as real-world word problems rather than pure equations. Practice translating sentences into mathematical expressions.
Master the on-screen calculator. The GED test provides a TI-30XS calculator for most questions. Familiarity with this tool saves valuable time. The GED Testing Service website offers a calculator tutorial.
Don’t just memorize — understand. Knowing that A = πr² is the area of a circle is useless if you can’t identify the radius in a word problem. Practice applying each formula in context.
Review one category at a time. Rather than studying all formulas at once, focus on one section per study session — geometry one day, algebra the next, statistics after that.
Take timed practice tests. Simulate real test conditions to build speed and confidence. The official GED practice tests available at ged.com are the most accurate representation of what you’ll face on test day.
Final Thoughts
The GED math test is absolutely passable with consistent preparation. You don’t need to be a math genius — you need to understand a finite set of formulas and know how to apply them. The formula sheet provided during the test gives you a safety net for geometry and coordinate formulas, but you need to bring your knowledge of algebra, statistics, and problem-solving strategies.
Start with the formulas you find easiest, build confidence, and gradually tackle the more challenging ones. Every formula on this cheat sheet represents points you can earn on the test. With regular practice and a solid understanding of these core concepts, you’ll be well-prepared to pass the GED Mathematical Reasoning test and move forward with your educational and career goals.