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Why are there ads?

We would love to provide everyone an ad-free experience, but we do need to generate revenue to cover at least some of our overhead. We're trying to be as reasonable as possible, and it also allows us to continue to offer you an option to access KenKen puzzles for free. For those who prefer an Ad-Free playing experience, we have an option for just pennies-a-day and it can be canceled anytime. BONUS! KenKen Premium also allows you to Track Your Progress, Join The Leaderboard, Save Puzzles, and more. Please consider this option for the best experience.

In addition, we continue to offer -- pro bono -- our KenKen Classroom Program which provides free KenKen puzzles and lessons to over 1 million students weekly. Revenue we raise from advertisements and subscription sales allow us to keep the program going, plain and simple. So thank you for supporting these teachers and students by supporting us. We all appreciate it.

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The Kenerator

Automatic Puzzle Producer

Mr. Miyamoto is a totally nice guy. But, as KENKEN grew, he was slightly hesitant to keep creating millions of new puzzles by hand, every day of the year, all by himself. (It would definitely cut into his scuba-diving time.) So the Kenerator was born: a complex artificial-intelligence computer program that generates and checks every new puzzle. The Kenerator was designed with the oversight and according to the specifications of Mr. Miyamoto, working side-by-side with leading artificial-intelligence expert David Levy.

When we run the Kenerator software we first set it according to various criteria, for example:

  1. The target difficulty level;
  2. How many "freebies" (single square cages) we want in the puzzle;
  3. Which arithmetic operations we want to be used in the puzzle;
  4. Which digits we want to be used in the puzzle (for example a 6x6 puzzle normally uses the digits 1-6 but we could, if we wished, specify it to be a different set of the digits taken from the whole range 1-9.
  5. Whether or not to show the arithmetic symbols in the puzzle (we can make the puzzles harder by omitting these symbols).

Then the Kenerator instantly verifies that each “cage” is correct, that no number appears more than once in a row or column, and most importantly, that each KENKEN puzzle has only one solution.

There is a module in the software, which pretends that it is a user and attempts to solve the puzzle. This module assesses the actual level of difficulty: easiest, easy, medium, or hard, employing a personalized algorithm based on a wide variety of factors. If the actual level of difficulty is as required, i.e. it conforms to the target set at the start of the Keneration process, then the puzzle goes into the "accepted" pile, otherwise it is rejected and the Keneration process starts over again.

And you thought we just picked the numbers out of a hat, didn’t you?

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General questions & Concerns: customercare@kenkenpuzzle.com

Welcome to KENKEN!

No matter what you're looking for — learning or fun — KenKen.com has it! Free online puzzles. Cool math games. Number games. (More addictive than Sudoku or Kakuro? You decide!) Educational games for kids. Visit our For Teachers section for math teacher resources, our free KenKen Classroom program, and a message from Tetsuya Miyamoto, the Japanese educator behind KenKen. Miyamoto, chess master David Levy, and the rest of Team KenKen have crafted these math puzzles into great games for learning and brain training. Need even more KenKen? Check out our Will Shortz Presents books. Try our mobile app on iPhone and iPad or our Kindle version. Play on the New York Times puzzle page and NCTM website. Regardless of why, how, or where you play, KenKen are the math puzzles that make you smarter!

Sincerely,
Team KenKen