Library

Calculators

12 calculators that teach: each one shows its working step by step, so you can follow it and do the next one yourself.

Numbers

HCF and LCMThe highest common factor and lowest common multiple of 2 to 5 numbers, by prime factorisation.FractionsAdd, take away, multiply and divide fractions and mixed numbers, simplified, with every step.

Percent and money

PercentagesA percentage of an amount, what percent one number is of another, percentage change, and back to the original.Simple and compound interestSimple interest (solve for the interest, the principal, the rate or the time) and compound interest year by year.

Algebra

Linear equationSolve ax + b = cx + d for x, moving the terms step by step.Quadratic equationSolve ax² + bx + c = 0: the discriminant, the kind of roots, the roots themselves and a check.Arithmetic progressionThe nth term, the sum of n terms, which term a number is, or the common difference.

Geometry and mensuration

Triangle: Pythagoras and areaThe hypotenuse or a leg of a right triangle, and the area from base and height or from three sides (Heron).Circle, arc and sectorFrom the radius, the circumference or the area, find the rest; and arcs, sectors and segments from an angle.Coordinate geometryDistance, midpoint, a point dividing a line in a ratio, the slope and equation of a line, and a triangle's area.Solids: surface area and volumeVolume and surface areas of a cube, cuboid, cylinder, cone, sphere and hemisphere.

Statistics

Mean, median and modeThe mean, median, mode and range of a list of numbers, with the working.