Repère, calcul mental

Mental arithmetic training site focused on large numbers and on diagnosing mistakes. It covers 15 skills across 5 levels, with an adaptive engine combining a smoothed mastery score, Leitner-box spaced repetition and weighted exercise selection. Every mistake is classified automatically (place value, missing zero, carry, swapped digits) and feeds a dashboard of charts. Game modes extend the training: an Everest climb, a 60-second blitz, a change-giving game, a duel and a multiplayer bomb game, synced through Supabase Realtime remotely or BroadcastChannel locally. Data stays in the browser through IndexedDB, with JSON export and import.