Calculus: Abacus & Mental Math

Make a little room for numbers. Calculus brings mental arithmetic and a hands-on Soroban abacus into one quiet daily practice. Work through a short session, move the beads, and revisit the answers that need another try. PRACTICE AT YOUR PACE Choose addition, subtraction, or a mix of both. Set 5, 10, or 20 exercises, with two to five numbers in each expression. Practice within 0–9 or 0–99. Take your time, or choose a one-, two-, or five-minute session limit. THINK WITH YOUR HANDS Explore an interactive five-column Soroban. Move beads to build numbers, or enter a number and see how it looks on the abacus. Six guided lessons introduce ones, fives, tens, and combining place values. ANSWER YOUR WAY Use the number keypad or the abacus during practice. Get feedback after each answer and keep moving at a pace that works for you. LEARN FROM EACH SESSION See your accuracy, correct answers, and time per answer. Review every exercise, then start a new session with just the exercises you missed. Your practice journal keeps completed sessions together. PICK UP WHERE YOU LEFT OFF Practice works offline. Your settings, journal, and unfinished session are saved on your device. Optional cloud backup is available from Progress on iOS and Android; it is tied to this device's identity and does not transfer your history to another device. No ads, subscriptions, or in-app purchases are included in this version. No sign-up form is needed to practice. Calculus focuses on addition, subtraction, and abacus basics. It does not teach advanced mathematical calculus. Support: hello@cochinescu.com Privacy and support: https://www.cochinescu.com/privacy