Math & Science Tools Calculators

This is the catch-all category for the academic arithmetic that isn't GPA-shaped. Significant figures are a shorthand for measurement uncertainty: a value reported to three sig figs is a claim about how precisely it was measured, and the rules for combining sig figs are really rules for not over-reporting precision in a derived result. Scientific notation is the same, expressed in a form where the sig-fig count is impossible to miscount. The quadratic solver reports the discriminant sign because that sign, not the roots themselves, is what usually answers the physical question — whether a projectile lands, whether a reaction has real solutions, whether an equation has crossings. The half-life calculator handles exponential decay, which shows up in radioactive dating, drug metabolism, and capacitor discharge with the same underlying formula.

How to use these tools

In multiplication and division, keep as many sig figs as the least precise input; in addition and subtraction, keep as many decimal places as the least precise input.
Scientific notation makes sig figs unambiguous: 1.5 × 10³ is two sig figs, 1.50 × 10³ is three, 1.500 × 10³ is four.
The discriminant (b² − 4ac) tells you before solving whether a quadratic has two real roots, one repeated root, or none; reading the sign is faster than running the formula when you only need existence.
Half-life math is the same equation regardless of the physical process: after n half-lives, the remaining fraction is (1/2)ⁿ.

Radioactive Half-Life Calculator

Compute the remaining amount of a radioactive substance after elapsed time, or solve for elapsed time given a remaining fraction. N(t) = N₀ × (1/2)^(t/T½).

Quadratic Equation Solver

Solve any quadratic equation ax² + bx + c = 0. See both roots, the discriminant, the vertex, and whether the solutions are real or complex.

Scientific Notation Converter

Convert between standard decimal numbers and scientific notation. Also see the engineering-notation form where the exponent is always a multiple of three.

Significant Figures Calculator

Count significant figures in any number, including decimals, scientific notation, and numbers with leading or trailing zeros. See which digits count and why.

Guides & articles

Mar 26, 2026

Significant figures in academic work: the rules that keep showing up on exams

Sig fig rules feel arbitrary until you realise they're a shorthand for measurement uncertainty. The five rules, explained with worked examples.

The math and science tools on this page are deliberately narrow in scope. The significant-figures and scientific-notation calculators answer exactly the questions the rules were designed to answer, without overreach. The quadratic solver returns roots and the discriminant sign; the half-life calculator returns the remaining fraction or the elapsed time. If a homework problem sits just outside what one of these tools handles — a cubic equation, a non-exponential decay model, a measurement with correlated uncertainty, a system that requires full error propagation — that's usually a sign to open a textbook rather than another calculator. These tools cover the common cases well and the uncommon ones not at all, by design.