Math Calculators

An answer on its own is only useful if you already trust the tool. These calculators show the working: the formula with your numbers in it, the intermediate values, and where the result came from. That makes them usable for checking homework, for teaching, and for the far more common case of wanting to be sure you have not mistyped something.

Everyday arithmetic

The percentage calculator covers the four questions people actually ask of percentages, and the percentage change calculator handles increases and decreases, where the order matters more than most people expect: a 20% rise followed by a 20% fall does not return you to where you started. The fraction calculator and decimal to fraction converter move between the two forms and simplify as they go.

Powers, roots and logs

The square root, cube root, exponent and logarithm calculators handle the cases a phone calculator makes awkward, including negative and fractional exponents and logs to any base. For very large or very small numbers, the scientific notation converter and the significant figures calculator keep the precision honest.

Number theory and sequences

Prime checking, prime factorisation, greatest common factor, lowest common multiple, modulo arithmetic, factorials, Fibonacci numbers and both arithmetic and geometric sequences each have their own page. They are the tools that turn a tedious manual process into something you can check in a second, which is most of their value: the answers are not hard, they are just easy to get wrong by hand.