Math that explains itself
Interactive, step-by-step calculators for high school and college — algebra through calculus, each one built to teach, not just answer.
Algebra
4 calculatorsQuadratic Formula
Solve ax² + bx + c = 0 — real or complex roots, with a graph.
Open calculator →Slope & Line Equations
Slope, every line form, distance and midpoint from two points.
Open calculator →Systems of Equations
Solve two linear equations and see where the lines cross.
Open calculator →Exponents & Roots
Powers and roots — negative and fractional exponents too.
Open calculator →Geometry
4 calculatorsPythagorean Theorem
Find a missing side of a right triangle, with a diagram.
Open calculator →Area & Perimeter
Area and perimeter for five common shapes, with diagrams.
Open calculator →Volume & Surface Area
Volume and surface area for six 3D solids.
Open calculator →Circle
Radius, diameter, circumference and area from any one.
Open calculator →Trigonometry
3 calculatorsTrig Functions
All six functions, quadrant and reference angle on the unit circle.
Open calculator →Law of Sines
Solve triangles from angle–side pairs (AAS / SSA).
Open calculator →Law of Cosines
Solve triangles from two sides + an angle, or all three sides.
Open calculator →Statistics
7 calculatorsMean, Median & Mode
The three averages, range and spread for any list.
Open calculator →Standard Deviation
Variance and standard deviation, sample or population.
Open calculator →Z-Score
Standardize a value and read its percentile on the bell curve.
Open calculator →Combinations & Permutations
Count the ways to choose or arrange items.
Open calculator →Confidence Interval & Hypothesis Test
Build a CI or run a test for proportions or means.
Open calculator →Linear Regression
Least-squares line, correlation and r² for paired data.
Open calculator →AP Statistics Score
Estimate your AP score on the new 2027 exam format.
Open calculator →Pre-Calculus
5 calculatorsLogarithms
Logs of any base, with change-of-base steps.
Open calculator →Sequences
Arithmetic and geometric terms and sums.
Open calculator →Binomial Theorem
Expand (a + b)ⁿ with the Pascal-row pattern.
Open calculator →Polynomial & Rational Functions
Zeros, end behavior, asymptotes and holes.
Open calculator →AP Precalculus Score
Estimate your AP score on the 2027 exam format.
Open calculator →Calculus
2 calculatorsCollege
2 calculatorsMoney Math
7 calculatorsLoan Payment
Monthly payment, total interest and a full amortization schedule.
Open calculator →Credit Card Interest
Average daily balance, daily rate and the interest charge, step by step.
Open calculator →Compound Interest
Growth with any compounding and monthly deposits, year by year.
Open calculator →APR to APY
Convert APR and APY for any compounding, or find APY from interest earned.
Open calculator →Savings Goal
How much to save each month for a goal, or how long it will take.
Open calculator →Present Value of Annuity
Present value, future value or payment of an annuity, exact to the cent.
Open calculator →Subsidized vs. Unsubsidized
Student loan interest during school and grace, plus the loan fee.
Open calculator →Everyday Math
3 calculatorsPercent Change
Percent change, percent difference, percentage points and reverse percents.
Open calculator →Weighted GPA
Weighted and unweighted GPA with AP, IB and honors classes.
Open calculator →Final Grade
The score you need on your final, or what a score does to your grade.
Open calculator →Formula Cheat Sheets
5 reference sheetsAlgebra Formulas
Slope, quadratic formula, exponent rules, factoring identities, sequences and more.
View sheet →Trig Identities
Pythagorean, reciprocal, double angle, half angle — all eight families with examples.
View sheet →Derivative Rules
Power, product, quotient, chain, trig, exponential and log — each with a worked example.
View sheet →Statistics Formulas
Mean, variance, z-score, probability rules, combinations and permutations.
View sheet →Geometry Formulas
Area, perimeter, volume and surface area for 2D and 3D shapes, plus angle relationships.
View sheet →AP Statistics Unit Guides
5 unitsUnit 1: Exploring Data
One-variable data and collecting data — 20–30% of the exam.
Read the guide →Unit 2: Probability
Random variables and distributions — 15–25% of the exam.
Read the guide →Unit 3: Inference for Proportions
Includes chi-square — 15–25% of the exam.
Read the guide →Unit 4: Inference for Means
t-procedures for one and two means — 10–20% of the exam.
Read the guide →Unit 5: Regression Analysis
Correlation and least-squares regression — 10–20% of the exam.
Read the guide →AP Statistics 2027 Changes
5 guidesFRQ Practice
Timed free-response practice with a 10-point self-scoring rubric.
Start practising →Old vs New Units
Map all nine old units onto the new five-unit structure.
Read more →Chi-Square Changes
Goodness of fit is gone — homogeneity and independence are not.
Read more →What Happened to Unit 9
Inference for slopes was deleted. Regression survives.
Read more →Topics Removed
Every topic cut from the course, with the nuances.
Read more →Calculator Guides
8 guidesDesmos & TI-84 Guide
Every 2027 procedure on Desmos and the TI-84, side by side.
Read the guide →Best Calculator for AP Stats
Is the built-in Desmos enough, and what is allowed in 2027.
Read more →TI-84 & Desmos Cheat Sheet
One printable page: every procedure, both calculators.
Open the sheet →Find a P-Value on Desmos
From a built-in test or a test statistic, with TI-84 steps.
Read the guide →Binomial on TI-84 & Desmos
Exactly, at most, at least and between.
Read the guide →Quadratic Formula vs Factoring
A ten-second check tells you which method to use.
Read the guide →Law of Sines vs Cosines
One question tells you which law to use, with worked examples.
Read the guide →Ambiguous Case (SSA)
0, 1 or 2 triangles: how to tell, and how to find the second.
Read the guide →AP Precalculus 2027 Changes
3 guidesWhat Changed for 2027
40→42 MCQ, revised timing, and a CED typo worth knowing.
Read more →Decimal Presentation Error
The FRQ scoring rule almost nobody explains.
Read more →Which Trig Identities Are Tested
Half-angle and tangent-sum identities are not on the exam.
Read more →