Mental math is a skill.
So we made it trainable.
Calculation isn't a talent you either have or you don't. It's a muscle. TauState turns thinking in numbers into something deliberate, a quiet daily ritual that compounds.
TauState is an intelligent mental-math training app for iPhone and iPad, built for anyone who wants sharper mental arithmetic. It offers 8 game modes and more than 40 operators, spanning the four basic operations, percentages, powers and roots, number theory, and number systems like binary, hexadecimal, and Roman numerals. Difficulty adapts automatically to the player's level, and a fully configurable Lab lets you build custom training sessions around exactly what you want to practise. TauState runs completely offline, with no accounts, no ads, and no tracking, and even its on-device speech recognition never leaves the phone. It's currently free during the TestFlight beta and requires an iPhone or iPad running iOS 18 or later. This website is available in German, English, Spanish, and French, though the app's own interface is German-only for now, with more languages planned.
Numbers as training
Every session is shaped around what you're actually working on, from the basics to number systems and number theory.
Progress over perfection
You don't need a perfect run. You need the next one. Difficulty adapts so you stay in the zone where growth happens.
A space to focus
No noise, no accounts, no distractions. Just you, the problem, and the satisfying moment the answer lands.
Built by someone who wanted to calculate.
TauState isn't the product of a big studio. It started as the personal training tool of a single developer in Germany, built to sharpen his own mental math for final exams. The tool became a project, and the project became an app that's as uncompromisingly private and focused as the one he wanted for himself.
Ready to elevate how you calculate?
Free on TestFlight. iPhone and iPad. Private by design.
Join the beta