Everything in the catalog

Calculates a confidence interval from sample statistics.

Checks whether two numbers are coprime and shows their common factors.

Finds the correlation coefficient for paired data.

Interactive practice counting coins and notes for young learners.

Tells which weekday any given date falls on.

Counts the days between two calendar dates.

Turns a decimal into a fraction, showing the steps.

Graphs equations in x and y, including implicit curves.

Practice guessing quantities and measurements against the real answer.

Shows how adding sine terms builds up a Fourier series.

Creates printable graph paper with chosen grid and axes.

Simulation of bodies moving under gravity that you can set up.

Finds the greatest common factor of two or more numbers.

Shades the region that satisfies one or more inequalities.

Approximates an integral using rectangles or trapezoids.

Finds the least common multiple of a set of numbers.

Fits a least-squares regression line to points you enter.

Evaluates an expression following the order of operations.

Solves quadratic equations and shows the roots and steps.

Finds the area, perimeter and diagonal of a rectangle.

Computes unions, intersections and differences of sets.

Gives volume and surface area of a sphere from radius or diameter.

Draws spirals from angle and length settings to explore geometry.

Drag a line on a graph to see its slope and equation change.