Balconia Math : 21 Marbles 4+

Logic puzzle for kids & adults

Elitza Maneva

Designed for iPad

    • 4.5 • 146 Ratings
    • $0.99



Try a new kind of math game in line with the Math Revolution envisioned by innovators like Youcubed and AOPS. Designed especially for children 6-11, "21 Marbles" doesn't quiz or time the player, instead it let's them enjoy thinking and reasoning.

A puzzle game's level progression is a natural "low floor, high ceiling" exercise. In the case of 21 Marbles, while the puzzles can become challenging enough to be enjoyed even by adults, the game has a friendly progression of difficulty that keeps everyone on board.

For the youngest players, it has the additional benefit of practicing the most basic arithmetic facts in an instinctive way. For the adults, it's like a relaxing peg solitaire game.

There are no instructions because the rules are natural and intuitive. 21 marbles - of colors and designs for all tastes - are won one by one. In every level, the recovered marbles - each representing the number 10 - break randomly into pairs of smaller marbles: either into a 9 and a 1, or an 8 and a 2, or a 7 and a 3, or a 6 and a 4, or two 5s. The marbles get positioned randomly on a board, and can be merged back together into 10s, by knocking together pairs that sum to 10. It is always possible to recover all 10s, but some thinking ahead is required. The "undo" button is always there to let you trace back your steps and find your mistakes. Learning to think ahead is not optional, and is the most important educational aspect of this game.

What’s New

Version 2.0.1

This app has been updated by Apple to display the Apple Watch app icon.

Sharing your progress with friends is now a click away. Actually, a click and a parental gate away, to be exact.

Ratings and Reviews

4.5 out of 5
146 Ratings

146 Ratings

murrayphd ,

Shucks. Does it really stop at 21?

It was just getting good! Of course game seems designed for kids, and as an adult, I have an advantage. The challenge level improves as the numbers get higher.

Developer Response ,

Thank you for your feedback! I am thinking of an infinite-play version to be added to a future update, so don't delete the game just yet (or check back later).

Flywithkids ,

Fun for all ages!

My daughter (age 9) played it till level 16, and I took up where she left off and completed it. It had a simplistic user interface but don’t let that fool you. The idea of the game is compelling like that of Tetris or the Chinese card game of 24. And the gameplay had pauses that let the mind rest a little. Kids of all ages will enjoy the earlier levels and grown-ups will enjoy the later levels.

Princess Evy ,


I loved playing this game…it really worked my brain.I was playing this game on a car ride and by the end of the car ride I had already done all 21 levels of the game and was so sad because it was so fun.I wish there were more levels!!!!

App Privacy

The developer, Elitza Maneva, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

You Might Also Like

Line Match!
Chroma Game - Match Colors
Sudoku ~ Classic Number Puzzle
Dot Line
Pixel Art Color By Number 2024
Flower Match Puzzle