Xumbers42 is a challenging brain teaser that will keep your brain fit and happy. It's a real time online game that's fun for all ages - if you can add, you will enjoy playing Xumbers.

Xumber42 is a crossword type game with words made of numbers instead of letters. Each Xumbers Word represents an additive equation.

Each player constructs Xumbers Words by combining the tiles in his/her tray with the tiles already on the board. In the screenshot above the horizontal Xumbers Word 257 stands for 2 + 5 = 7, and the vertical Xumbers Word 82212 stands for 8 + 2 + 2 = 12.

The score for each move depends on the length of the Xumbers Word; longer words mean higher scores.

Advanced players create long Xumbers Words by extending existing Xumbers Words. For example, the vertical Xumbers Word 756189642 was created first by extending 6 to 75618 (7 + 5 + 6 = 18) and then by extending 75618 to 756189642 (7 + 5 + 6 + 1 + 8 + 9 + 6 = 42).

The Xumbers Story:

Mathematician, math educator and software developer Marc Konvisser, Ph.D. originally created Xumbers so that his granddaughter would have an enjoyable way to learn her addition facts.

Once the game was completed, he started playing Xumbers himself, at first for debugging, but soon just because it was fun. He was pleasantly surprised to discover that the game, which was conceived as a children's learning tool, was engaging and challenging for adults.