(Open Source) Mental Math vs Numvolt

A free, open-source mental math trainer. No ads, no paywalls, no locked content — every exercise and difficulty is included. Sharpen your arithmetic with quick timed tests, custom drills, and a library of mental-math tricks. Everything runs offline and your progress stays on your device. FEATURES Timed Tests A daily 60-second challenge plus sprints, a two-minute marathon, per-operation tests, and a hard mixed test — at four difficulty levels, each with best scores. Custom Trainer Pick a number domain (Times tables, Natural, Decimal, Money, Huge), choose one or more exercises, and set per-exercise difficulty from Easy to Super hard. All the Operations Addition, subtraction, multiplication, division, squares, square roots, fractions, percentages, and modulo. Mental Math Tricks Dozens of step-by-step tricks for faster addition, subtraction, multiplication, division, and squares — with worked examples and favorites. Practice Any Trick Every trick comes with a 60-second drill built for it: × 11 drills, squares ending in 5, numbers near 100, and more. Magic Square A number puzzle: make every row, column, and diagonal add up to the same total. Four levels, from 1-9 up to bigger number sets. Progress Tracking Solved totals, accuracy, best run, daily streak, longest streak, and a weekly activity view. Fast Sessions An on-screen keypad with instant answer checking and haptics. No ads. No paywalls. No account required. 100% Open Source The complete source code is public - see it, audit it, or contribute at https://github.com/Open-Apps-Studio/mental-math

Numvolt helps you get better at mental math: open, calculate, understand, repeat. No account and no ads. For new installations, Numvolt Pro is required to start sessions after onboarding. Choose a yearly subscription or a lifetime one-time purchase; the price and terms are shown before purchase. FIFTEEN TOPICS, A HUNDRED AND FIFTY RUNGS EACH Addition, subtraction, multiplication, division, fractions, percentages, order of operations, powers, algebra, square roots, signed numbers, proportions, time and durations, unit conversion and number patterns. Each topic has its own 150-rung journey, up to five elite chapters; the difficulty adjusts during the session, block by block. You pick your starting point at setup, and you can always replay a lower level. THE FASTEST METHOD, FOR EVERY CALCULATION After a mistake, and at the end of a session for your slowest answers, Numvolt shows you the fastest way to do it in your head, step by step: 71 × 87 is 70 × 87 + 87; 79² is 80² − 160 + 1. With the reflex to keep and other ways to do it. In the courses, type any calculation and the app explains the best method. In Zen mode there is no timer: time to understand. SPRINTS AND A DAILY CHALLENGE 15, 30 or 60 seconds on the + − × ÷ mix. +1 per correct answer, −1 per mistake. The daily challenge is the same 60-second series for everyone, all day long. A LADDER FROM YOUR CITY TO THE WORLD Join the ladder with a nickname and your city. Your best sprint is ranked on six rungs: city, county, region, country, continent, world. After every sprint you see exactly what you climbed — "5th → 2nd · Rhône" — and how many points you need to overtake the next player. Only your nickname, city and scores are published. Never your exact location. DUEL ON ONE PHONE Two players, the same questions in the same order, 30 seconds each. Scores are revealed at the end. YOUR PROGRESS, VISIBLE XP, overall level, accuracy, day streak, seven-day chart, level per topic and session history. A Home Screen widget shows your daily goal and starts a sprint in one tap. WHAT STAYS WITH YOU Your progress lives on your iPhone, in the app's storage. No account. Anonymous usage counters, which you can switch off in Settings, only tell us where the app gets stuck. Fractions and decimals accepted on the keypad. Light, dark or automatic appearance. Available in 46 languages. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/