Short, plain lessons on the math people search for most. Each one explains the idea, lists the steps, works one example completely, warns about the usual mistakes, and links to a free helper where you can try your own problem.
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Grades 3–5
Grades 6–8
- Order of operations (PEMDAS)Order of Operations (PEMDAS), Step by Step
- Negative numbersHow to Add, Subtract, Multiply and Divide Negative Numbers
- Prime factorizationHow to Find the Prime Factorization of a Number
- GCF and LCMHow to Find the GCF and LCM of Two Numbers
- Simplifying fractionsHow to Simplify Fractions, Step by Step
- Adding fractionsHow to Add Fractions with Unlike Denominators
- Multiplying fractionsHow to Multiply Fractions and Mixed Numbers
- Dividing fractionsHow to Divide Fractions: Keep, Change, Flip
- Fractions to decimalsHow to Convert a Fraction to a Decimal
- Decimals to fractionsHow to Convert a Decimal to a Fraction
- Improper fractions and mixed numbersHow to Change an Improper Fraction to a Mixed Number
- Multiplying decimalsHow to Multiply Decimals, Step by Step
- Percent of a numberHow to Find a Percent of a Number
- Percent changeHow to Calculate Percent Change (Increase and Decrease)
- Discounts and sale priceHow to Calculate a Discount and the Sale Price
- Ratios and proportionsHow to Solve Proportions (Ratios), Step by Step
- Unit rate and best buyHow to Find a Unit Rate (and the Better Buy)
- Unit conversionsHow to Convert Units (Dimensional Analysis)
- Mean, median and modeHow to Find the Mean, Median and Mode
- Box plotsHow to Make and Read a Box Plot (Five-Number Summary)
- Probability basicsProbability Basics: How to Find the Chance of an Event
- Area of a circleHow to Find the Area of a Circle
Algebra and geometry (grades 8–10)
- Two-step equationsHow to Solve Two-Step Equations, Step by Step
- Systems of equationsHow to Solve a System of Equations (Elimination Method)
- Slope from two pointsHow to Find the Slope of a Line from Two Points
- Slope-intercept formSlope-Intercept Form (y = mx + b), Step by Step
- Factoring quadraticsHow to Factor Quadratics (x² + bx + c), Step by Step
- Quadratic formulaHow to Use the Quadratic Formula, Step by Step
- Completing the squareHow to Solve by Completing the Square
- Exponent rulesExponent Rules: How to Simplify Powers, Step by Step
- Scientific notationHow to Write Numbers in Scientific Notation
- Simplifying square rootsHow to Simplify Square Roots, Step by Step
- Pythagorean theoremThe Pythagorean Theorem, Step by Step
- Volume of a cylinderHow to Find the Volume of a Cylinder
- Arithmetic sequencesArithmetic Sequences: Find the nth Term and the Sum
- SOH CAH TOA (sin, cos, tan)SOH CAH TOA: How to Use Sine, Cosine and Tangent
High school, college and beyond
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