Comparison

SKoolKool vs Millennium Problems

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

SKoolKool

Features
Read full description

SKOOLKOOL — STUDY SMARTER, NOT HARDER The only free study app that turns your PDFs, YouTube videos, and textbooks into flashcards, quizzes, and learning games — in seconds. No subscriptions. No paywalls. Everything, always free. LEARN 4 WAYS Subjects — Structured lessons from beginner to advanced Study — Spaced repetition, active recall & 7 smart study modes Games — Reinforce what you learned through competitive gameplay Notes — Organized notes linked to your flashcards automatically AI GENERATES YOUR STUDY MATERIAL Upload a PDF, paste a YouTube link, or point at any textbook — SKoolKool's AI creates optimized flashcards and quizzes instantly. Works for any subject: medicine, law, languages, engineering, history, and more. ALREADY USE ANKI? Import your existing Anki decks in one tap and keep studying without starting over. STUDY WITHOUT INTERNET Download your content and study anywhere — on the subway, on a flight, anywhere offline. BUILT FOR EVERY STUDENT MCAT · LSAT · USMLE · Bar Exam · GRE · AP Exams · University Finals · Language Certifications · Professional Licenses LEARN TOGETHER Explore community-created decks for popular subjects Share materials with classmates Collaborate in real-time study groups Teachers: generate tests from lecture slides and track student progress instantly WORKS WITH EVERYTHING PDFs · YouTube Videos · PowerPoint · Web Articles · Handwritten Notes (via photo) · Plain Text 100% FREE. ALWAYS. Unlimited flashcards, quizzes, games, and notes — no credit card, no trial, no catch. Download SKoolKool and turn your next study session into something you actually enjoy.

About

Millennium Problems

Explore seven unsolved mathematical mysteries, each with a million-dollar prize. This app adapts content for all skill levels, from middle schoolers to doctoral researchers, with interactive 3D visualizations and built-in quizzes. Learn at your own pace, offline, with no ads or subscriptions.

Highlights
  • Explains seven major unsolved math problems
  • Content adapts to skill level (Grade 6 to Graduate)
  • Interactive 3D visualizations
  • Built-in quizzes with XP and badges
  • Offline functionality
  • Optional biometric lock
Features
Read full description

Can you solve a problem worth $1,000,000? The Clay Mathematics Institute has offered a million-dollar prize for each of seven unsolved mathematical problems — and nobody has claimed them yet. Millennium Problems brings these mysteries to life for everyone, from curious 11-year-olds to doctoral researchers. SEVEN LEGENDARY PROBLEMS • P vs NP — Is finding as hard as checking? • Riemann Hypothesis — Where do prime numbers hide? • Yang-Mills & Mass Gap — Why do particles have mass? • Navier-Stokes — Can we predict turbulent fluids? • Hodge Conjecture — What shapes are built from algebra? • Birch & Swinnerton-Dyer — How many solutions does an equation have? • Poincaré Conjecture — The shape of the universe (SOLVED!) EVERY SKILL LEVEL Choose your grade — from Grade 6 to Graduate — and the content adapts instantly. The same problem is explained with simple analogies for a middle schooler and rigorous proofs for a PhD student. INTERACTIVE 3D VISUALISATIONS Every problem comes with a real-time Three.js visualisation. Watch elliptic curves rotate, Riemann zeros appear on the critical line, and fluid particle fields swirl — all rendered natively on your device. BUILT-IN QUIZZES Test your understanding with 5 questions per problem per grade level. Earn XP, track your streak, and collect badges as you explore. WORKS OFFLINE No account. No subscription. No ads. Everything runs locally on your device. OPTIONAL BIOMETRIC LOCK Protect your progress with Face ID, Touch ID, or fingerprint — entirely optional. Whether you're a student looking for a challenge, a teacher seeking engaging material, or a mathematician revisiting the classics, Millennium Problems meets you where you are. Clay Mathematics Institute · $7,000,000 in unclaimed prizes · Since 2000

Screenshots

SKoolKool4 screens
Millennium Problems4 screens

Verdict

The call

The clearest difference is update cadence: Millennium Problems at every 4 days against SKoolKool's every 10 days. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

SKoolKool ships an update every 10 days, Millennium Problems every 4 days. The most recent releases landed on October 7, 2026 and October 9, 2026 respectively.

Scorecard1 real difference · 8 level
SKoolKool versus Millennium Problems: the parameters behind the verdict, then further details
ParameterSKoolKoolMillennium Problems
PriceFreeFree
Rating—5.0 (1 ratings) — better
Number of ratings—1 — better
Update frequencyEvery 10 daysEvery 4 days — better
AdsNoNo
In-app purchasesNoNo
Monetization—Free
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.115.0 — better
Further details — not scored
Size47 MB9 MB
Age rating12+4+
DeveloperBoudjemaa DJEBARRILoic Fonkam

In-app purchases

None

SKoolKool

No in-app purchases

None

Millennium Problems

No in-app purchases

Questions

Is SKoolKool free?
SKoolKool is free to download, with no in-app purchases.
Is Millennium Problems free?
Millennium Problems is free to download, with no in-app purchases.
Do SKoolKool or Millennium Problems have ads?
Neither SKoolKool nor Millennium Problems shows ads.
Which is updated more often, SKoolKool or Millennium Problems?
SKoolKool ships an update every 10 days, and Millennium Problems every 4 days. Most recently, SKoolKool was updated on October 7, 2026 and Millennium Problems on October 9, 2026.

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