Number Spark
Match factors, make a spark, score big
A new puzzle every day for everyone to share!
Everyone in the world gets the same shuffle of the numbers 1 to 64. Set off chain reactions of shared factors to clear them all, then see how your score stacks up on the daily leaderboard.
On mobile? [Tap Here to Open Full Screen]
New to Number Spark? Tap Tutorial on the start screen for a quick walkthrough. You can replay the tutorial anytime from the ⚙️ menu.
How to Play
Tap a number to see its factors. The board holds 16 numbers at a time. As you clear them, new ones drop in from above until all 64 have appeared.
Pick a factor to spark it. Neighbors above, below, left, and right that share that factor spark too, and the chain keeps going.
Watch for special tiles. Sparking a prime sets off every prime connected to it. The 1 is wild and can spark any factor its neighbors have.
Don't waste sparks. You start with 5. A number that sparks alone costs you one, and when you run out, the game is over.
Clear all 64 to post a score. Play as many times as you like. Every run that clears the board goes on today's leaderboard, and tomorrow brings a new shuffle.
How Scoring Works
TL;DR: long chains that start with a prime number pay off.
Start the spark chain on a composite number and each tile in the chain adds a higher power of the factor you sparked: for example if the factor sparked was 3, the second tile would count as 9, then 27, etc.
Start on a prime and each tile multiplies into a running total, for example: 2, then 2 × 3, then 2 × 3 × 6.
One big chain will beat a lot of small ones.
The ⚙️ menu has a scoring playground where you can try it with a basic set of numbers.
Why I made Number Spark
For 20 years I've been trying to change how people feel about math, in classrooms and through games like MULTI and Numeroso. Number Spark is my latest attempt to get people to see math as fun and accessible, at scale.
Wordle proved a tiny daily puzzle can become a shared ritual: same puzzle, same day, scores flying around group chats. I want that for math. A small, positive moment with numbers every day, and something to connect with each other about.
My hope is that Number Spark builds a community of players and finds its way into classrooms, kitchen tables, and everyday conversations. Not as homework. As something people look forward to.
Number Spark grew out of a game I designed for Numeroso cards, and I built it with my longtime friend and advisor Charlie Van Norman. And with the help of my friends Dean Sitton and Jody McLain who play tested and advised on UI/UX design.
— Federico Chialvo, founder of Joyful Mathematics
Better with friends
Share your score. When you clear the board, tap Share Your Score to send the puzzle number, your score, and a grid showing your biggest chain. Send it to a friend, a sibling, or the coworker who swears they're "not a math person."
Climb the leaderboard. Pick a three-letter tag, or sign in to use a username. You can also look back at past days' boards.
Keep your streak alive. The game tracks how many days in a row you've made the leaderboard, and your spark glows hotter the more days you play.
Talk about it. Everyone played the same numbers, so there's always something to compare:
What was your first spark? Would you change it?
What was your biggest chain?
Which number was hardest to clear?
Which prime gave you the most trouble?
Stay in the loop. Get strategy tips, new features, and ideas for playing with kids and classes.
Number Spark in the classroom A daily puzzle for prime factor fluency
Every student gets the same numbers, which makes Number Spark a ready-made warm-up. Give the class five minutes to play, then compare strategies using the questions above.
The math inside. Factors and multiples, primes and composites, common factors, and prime factorization. Before long, students notice that 64 is nothing but 2s, and that 49 can only connect through 7 (or the wild 1).
Grades 4 and up. Supports 4.OA.B.4 (factors, multiples, prime vs. composite) and 6.NS.B.4 (common factors).
Classroom ready. No accounts or downloads. It runs in a web browser on computers, tablets, and phones. Just point your browser at numberspark.com
Teacher’s Guide Coming Soon…
FAQ
Is it free? Yes.
Do I need an account? No. Anyone can play and post to the leaderboard. Signing in with your email is optional; it lets you pick a username and keep your stats across devices.
When does the new puzzle drop? Every day at midnight Pacific time (3 a.m. Eastern).
Who is it for? Anyone who can dig it! Kids as young as 6 have figured out how to play, while its academically aligned with many of the 3-6th grade standards, and helps build fluency with prime factorization which is a critical skill for Algebra and beyond. That said Number Spark can be enjoyed by humans of all ages and backgrounds.
What devices does it work on? Any device with a modern web browser, touchscreen or mouse.
What shows on the leaderboard? Rank, score, and a three letter gamer tag.
More from Joyful Mathematics
Love Number Spark?
Play it with cards. Numeroso is the card game Number Spark grew out of.
MULTI is tic-tac-toe played on a multiplication table.