This puzzle is essentially a Latin square with addition. All you really need to know is how to add single-digit numbers, although subtraction is also useful. Once you’ve spend a few minutes sorting out which numbers mean what, you’re ready to start puzzling!

• Getting started
• Classroom demonstration
• 4x4 puzzles (and solutions , just in case)
• 5x5 puzzles (and solutions )
• 6x6 puzzles (and solutions )
• Puzzles in three sizes

Once you’ve mastered these, you might enjoy creating your own puzzles: just start with the tick and X-marks, work out the sums, then decide how many of the sums to give as clues.

I think this puzzle was invented by Otto Janko.  Check out his website for this and many other intriguing games.

Here is another on-line Kaurasu generator .  Although the site is in Polish. it’s pretty self-explanatory!

• puzzles