Which Formula

Stuck on a math problem because you can't tell which method it wants? Which Formula answers that one question, and leaves the working to you.

There's nowhere to type an equation, on purpose. The app names the right tool, shows you how to use it and warns you about the mistakes it invites. Every step of your own problem stays yours.

FIND MY METHOD

Answer a few questions about what the problem looks like: where the variable sits, whether the triangle has a right angle, what you were given. Your answers are drawn down the page as a flowchart until you land on one method, with its formula, its steps and a short throwaway example of its shape. Most options show a tiny example too, so it works before the vocabulary does. You don't need to know the words "rational equation" to recognize 1/x + 2 = 5.

39 methods, reached through 15 questions.

SPOT THE METHOD

Five problems a day, the same five for everyone. For each one you pick which of four methods you'd start with. You don't solve anything. Get it wrong and you see which method it was and why. Keep a daily streak going, or run a practice round any time, and practice leans toward the methods you've been missing. 195 problems across every topic.

THE CHEAT SHEET

Twelve reference topics for when you already know what you need and just want the formula in front of you:

• Logarithms and exponentials: conversions, ln, log properties, domain
• Exponent rules, radicals, rationalizing
• Quadratics: formula, discriminant, vertex, completing the square
• Polynomials: factoring patterns, division, root theorems, end behavior
• Rational expressions: simplifying, LCD, complex fractions, asymptotes
• Complex numbers: powers of i, arithmetic, conjugates
• Systems of equations: substitution, elimination, and what no solution looks like
• Sequences and series: arithmetic, geometric, finite and infinite sums
• Functions and transformations: shifts, stretches, inverses, composition
• Right triangle trig: SOH-CAH-TOA, reciprocals, inverse trig
• Unit circle and angles: key angles, degrees and radians, quadrant signs
• Trig identities: Pythagorean, sum and difference, double angle, both laws

Search finds a formula by name or by a piece of it.

It looks like a math notebook: graph paper, pen and a highlighter. Works in English and Spanish, works offline, and there's no sign-up.

It's free, with a small banner ad at the bottom of the home page, the cheat sheet and the method pages. Find my method and Spot the method have no ads, because that's where you're thinking.

For Algebra 2 and Trigonometry students, and anyone brushing up before precalculus or a placement test.