Ninja Numbers
BECOME A MATH NINJA
IN JUST 3 MINUTES A DAY
Master your speed and accuracy!
No login required to start practicing.
🥋 Earn Belts by Mastering Math Levels
🥋 Addition Belt
📝 Custom Math Speed Test
× Dojo Grid
Track which multiplication facts you’ve mastered (0–12 × 0–12).
Practice below here, or do multiplication in Earn Belts, Custom Test, or Challenge to update the grid!
🏆 Compete
Choose your difficulty level. Then, take the test and compete for your fastest time! Only perfect scores show up on the leaderboard.
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🥋 My Progress
Your belts and what’s left to earn.
Ninja Numbers
BECOME A MATH NINJA
IN JUST 3 MINUTES A DAY
Master your speed and accuracy!
No login required to start practicing.
About Ninja Numbers
Why use Ninja Numbers?
Higher math needs solid basics. Many schools stopped drilling students with flash cards. Use Ninja Numbers to build a strong math foundation!
Knowing a math fact isn’t enough; we need to recall it instantly. Timed practice builds that “speak math” instinct, so the brain can focus on the harder stuff!
Math should be fun! With regular practice, you can earn belts, stars, and compete against others for the fastest times.
How to use Ninja Numbers?
Progress through five belts (inspired by martial-arts ranks): White (addition), Blue (subtraction), Purple (multiplication), Brown (division), and Black (mixed operations—unlocks after the first four). Complete each level with at least one star to earn the belt; get 2 or 3 stars on every level in the track to earn 2 or 3 stripes. We recommend a free account to save your progress and belts across devices.
Choose your operation(s), number range, and how many problems—then run a custom drill. No belt required; great for targeted practice on exactly what you need.
See how you stack up on speed and accuracy. Sign in to submit your time and climb the ranks.
The Dojo Grid shows which multiplication facts (0–12 × 0–12) you’ve practiced and which you’ve mastered. Each cell turns green after you get that fact right 4+ times, yellow after 1+ correct, and stays gray until you’ve tried it. Progress updates when you do multiplication in Earn Belts, Custom Test, or Challenge—or use the timed practice right on the Dojo tab. Sign in to see and save your grid.
FAQ
We believe that with just a little bit of practice each day, you can learn to master math skills. It takes consistent practice over several days to master, but it shouldn't require a super long commitment. Though, please feel free to play as long as you would like here!
We recommend using a keyboard with a number pad. Then, use the Tab button to move to the next question. At the end, you can hit Tab and then Enter to submit your answers for grading.
Please keep trying! Don't give up! It may help to go back to an easier level and master that one too.
Data usage
We keep things minimal and transparent:
- Without an account: Progress is stored only in your browser (localStorage). We don’t collect or store it on our servers. Clearing site data will reset progress.
- With an account: We store your email (for login), optional display name and avatar, and your progress (levels completed, stars, belts earned) so you can pick up where you left off on any device. Scores you submit in Compete use your display name.
- Cookies and local storage: We use cookies and local storage for login, saving progress, and preferences (e.g. theme). Sign-in with Google may set cookies on Google's domain. We do not use advertising or tracking cookies.
- We do not sell your data. We use it only to run the site (auth, saving progress, Compete) and to improve the product (e.g. aggregated, non-identifying analytics).
- You can delete your account and associated data by contacting us at help@ninjanumbers.io.
Age & supervision
Ninja Numbers is intended for users 13 and older. Parents are responsible for creating, managing, and supervising accounts for any children under 13 who may use this app.
Terms of use
By using Ninja Numbers you agree to the following:
- Use as-is. The service is provided “as is” without warranties of any kind. We do not guarantee uninterrupted or error-free operation.
- Limitation of liability. To the fullest extent permitted by law, Hovercraft AI Services LLC and its affiliates are not liable for any indirect, incidental, or consequential damages arising from your use of the service.
- Changes. We may update these terms from time to time. Continued use of Ninja Numbers after changes constitutes acceptance of the updated terms. Important changes may be noted on the site or via email where appropriate.
- Questions. For questions about these terms, contact us at help@ninjanumbers.io.
Contact us
For account or data questions, contact us at help@ninjanumbers.io. We also welcome feedback to make Ninja Numbers better.
Ninja Numbers is part of Hovercraft AI Services LLC.