About PiNumpad. Tau

PiNumpad is a free memory trainer for tau (6.28318530717958...), tau, equal to 2π, the ratio of a circle's circumference to its radius. This page explains how tau is implemented in the trainer, grouping logic, colour coding, and anything specific to this constant.

About this constant on PiNumpad. The About page explains how this particular constant is implemented in PiNumpad: how the digits are grouped, what the colour coding means, and any notes specific to this constant that differ from the others.

Tau simplifies many formulas involving circles and radians, a full turn is τ radians, not 2π. It has a dedicated following among mathematicians who argue it is the more natural circle constant. Check this page if you are new to PiNumpad and want to understand the grouping logic before you start, or if you are switching from another constant and want to understand the differences.

PiNumpad is designed for maths students, engineers, programmers, and advocates of the tau manifesto who prefer their circle constants in terms of radius rather than diameter. It runs entirely in the browser with no account, no installation, and no cost. Progress is saved locally using your browser's storage.

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