Zahlenschatzjagd ("number treasure hunt") lets children in their first two school years practise maths on their own – offline, without ads and without a single permission. It is made for children who cannot read yet: pictures and a voice that reads everything aloud show the way. The app and all its texts are in German only. It follows the maths curriculum for primary schools in North Rhine-Westphalia and speaks to German-speaking children and parents. Exercises: addition, subtraction, multiplication and division up to 10, 20, 50 or 100, doubling, number walls, number bonds to 10, comparing numbers and finding neighbouring numbers. A treasure chest fills up for each exercise, from bronze to platinum. For parents, behind a small sum or a PIN: what a child practised recently and how confident it is, a practice calendar, which exercises a child may use, sound and read-aloud settings, and a backup file of all progress for moving to a new device. Several siblings can share one device, each with their own profile and progress. No permissions, no tracking, no account – all data stays on the device.