Mathematics formulas with the working shown in full. Each page explains where the formula comes from, when it applies, and what the answer means once you have it — then solves your own values step by step.
Formulas in this section
- Pythagoras’ theorema² + b² = c²Find any side of a right-angled triangle from the other two.Grades 9–10
- The quadratic formulax = (−b ± √(b² − 4ac)) ⁄ 2aSolve any equation of the form ax² + bx + c = 0.Grades 9–10
- Arithmetic progressionaₙ = a + (n − 1)d, Sₙ = n⁄2 (a + aₙ)Any term, or the sum of a run of terms, in a sequence that steps by a fixed amount.Grades 11–12
Rearranging is the part that trips people up
The hardest part of school mathematics is rarely the arithmetic. It is knowing which formula the question is asking for, and being confident rearranging it when the unknown is not where the textbook put it. These pages are built around that: every solver will find whichever value you leave blank, and the working names the move it is making at each line.