Cosuki: Learn Algebra

Learn Algebra. Actually Understand It. Cosuki is an algebra learning app built around one simple idea: understanding comes before memorization. Learn the concept. Follow a worked example. Practice it yourself. Then prove you’ve mastered it. From variables and expressions to the Grand Trial, Cosuki takes you through 10 carefully structured chapters covering inequalities, coordinate geometry, systems of equations, exponents, polynomials, quadratics, functions, and more. LEARN WITH PURPOSE Every chapter starts with clear concept guides that explain the rule, demonstrate a worked problem, and walk you through the reasoning behind every step. Then it’s your turn. Complete practice missions, build confidence, and finish with mastery tests designed to make sure the concept actually stuck. Each chapter includes 22 missions and 110 questions. When you make a mistake, Cosuki doesn’t just mark it wrong. It explains what happened and helps you understand the solution. When you’re stuck, hints help you move forward without simply giving away the answer. EARN YOUR PROGRESS Learning is the journey. The treasures are the proof. Complete chapters to collect 10 hand-painted rewards, from the Scholar Headband to the Grand Trial Armor. Equip your favorites and make your journey your own. HEARTS THAT ENCOURAGE CARE You start with five hearts. A wrong answer costs one, and hearts replenish automatically. They aren't here to punish mistakes. They’re a small reminder to slow down, read carefully, and think before you answer. PRIVATE BY DESIGN Cosuki is built to respect your privacy from the ground up. No ads. No subscriptions. No account. No sign-up. No email address. No analytics. No tracking. No advertising identifiers. There is no Cosuki server collecting your personal information. Your progress stays on your device and is backed up through your own Apple account. Reinstall the app without losing your progress. And because your lessons are stored locally, Cosuki works completely offline. Your learning belongs to you. START FOR FREE Chapters 1 and 2 are completely free. That’s 44 missions and 220 questions with no time limit, no trial, and no credit card required. When you’re ready for the full journey, Cosuki Plus unlocks the remaining eight chapters with a one-time $4.99 purchase COSUKI PLUS • All 10 chapters • 7 hearts instead of 5 • 3 hints per mission instead of 1 • One-time purchase • No subscription • No recurring charges Buy it once. Keep it forever. No subscriptions. No renewals. No surprises. THE GRAND TRIAL AWAITS Start with the fundamentals. Build your understanding one idea at a time. Master the concepts. Then prove how far you’ve come. Welcome to Cosuki.