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 is the practice mode: the numpad path is hidden and you tap tau digits entirely from memory. Your score is saved locally between sessions.

Practice from memory. In play mode, the numpad path is hidden. You must tap each digit of the sequence from memory alone, with no visual guide. A correct tap advances the path; an incorrect tap triggers a brief error sound and a shake. Your score, the number of digits or primes you can enter without error, is stored locally so you can track progress across sessions.

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. Tap the digits on the on-screen numpad in the correct sequence. Use Study mode first to learn the path, then switch to Play to test retention. Hold the hint button to reveal the path briefly if you are stuck.

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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