Speed mental math trainer with a twist, your score fights back. The Numerlo Index is a dynamic ranking system inspired by neuroplasticity and chess Elo. It tracks your mental math ability and drops if you stop training. The core game is simple: solve as many mental math questions as you can in 60 seconds. Questions get harder as your score climbs. Additionally, professional practice modes for finance, accounting, sales, medicine, actuarial and engineering because mental math shows up everywhere.