This app allows to improve mental calculation skills easily and quickly. Our app are ideal for kids making their first steps in learning math, as well as for adults who want to train their brain. Keep your brain fit through regular math exercises. Your brain will work faster and more efficiently. Topics: 1. Addition and subtraction within 10 2. Addition and subtraction within 20 3. Chains of examples within a 10 4. Addition and subtraction of two-digit and one-digit 5. Addition and subtractio