Maths SolverStep-by-step maths, written by people who teach it.
We publish long-form guides on the high-school and first-year university topics that students actually get stuck on — quadratics, derivatives, the Pythagorean theorem — and pair each one with a small calculator that shows every step of the work, never just the final answer.
Featured guides & calculators
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Quadratic equations: from intuition to the formula
Why the discriminant tells you the number of roots before you ever apply the formula, three ways to solve
x² − 5x + 6 = 0by hand, and the mistakes I see most often when students use the formula on a test. -
Derivatives, properly explained
What the derivative actually measures (and what it doesn’t), how the power, product, quotient and chain rules drop out of the limit definition, and how to recognise which one to use without guessing.
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The Pythagorean theorem, four different proofs
A diagram-driven walk through the most famous identity in geometry, with a visual rearrangement proof, an algebraic proof, a similar-triangle proof, and the converse you need for SAT and GCSE problems.
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Systems of linear equations: substitution & elimination
Solving 2×2 systems of equations by substitution and elimination, when to use each method, and how to spot special cases like parallel lines and identical lines algebraically.
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Definite integrals and the area under a curve
The Riemann-sum definition, the fundamental theorem of calculus, and how to evaluate a definite integral by antidifferentiation. Pairs with a step-by-step numerical integration calculator.
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Limits, and why epsilon-delta is not as scary as it looks
The intuitive definition of limits, how to handle indeterminate forms (0/0, ∞/∞) using factoring and L’Hôpital’s rule, and a step-by-step solver.
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Percentages: the three things you can be asked
Mastering the three types of percentage questions (finding the percentage, finding the part, and finding the whole) with a unified algebraic approach and an interactive calculator.
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Age word problems, demystified
How to translate English age puzzles into clean systems of linear equations, and a step-by-step solver for two-person age problems.
From the blog
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How to avoid silly mistakes in maths exams
The three types of silly mistakes students make on maths exams (sign errors, misreading the question, and calculator slips), how to prevent them, and a 10-minute check strategy.
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What a proof actually is, and why mathematicians won’t let it go
A proof is not a “convincing argument.” It is the difference between believing something and knowing it. A worked example, three styles of proof, and why even non-mathematicians benefit from learning to write one.
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How SAT Math scoring actually works on the digital test
The two-module adaptive structure, what your score on Module 1 does to Module 2, and why the “raw to scaled” conversion is more interesting than the College Board lets on.
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The week before a maths exam: what I would and would not do
The case against last-minute revision, what to actually do with the seven days, and the morning-of routine I have given to every Year 11 I have ever taught.
Browse by topic
Each section contains in-depth lessons and step-by-step calculators designed to help you verify your steps and master the curriculum.
Who writes this
Maths Solver is run by two former classroom teachers, Daniel Whitman and Sara Lin. We started the site after years of writing the same explanations on whiteboards for one student at a time, and eventually deciding the explanations might be more useful as something we could actually link to. Everything is free; the site is supported by unobtrusive display ads. There is no app, no premium tier, and no login. You can read more about the project here or get in touch if you spot a mistake.