Cross Sums, now trendily known as Kakuro, have always been my favorite pencil puzzle. I also think they’re great for students. They involve practice in logical reasoning, mental math, and summing sequences.
I have found several sources for free printable Kakuro puzzles online. My favorite is Krazy Dad but I also like Kakuro.net (these print with a large color advertisement on each page — I highly suggest changing your print mode to gray scale to save your color ink). Kakuro Puzzle has two daily printable puzzles (easy and challenge), plus 3 huge “impossible” kakuros. AKidsMath also has multiplication puzzles, which I haven’t played with much yet, but seem like they would be great for reinforcing factoring skills!
The thing is, I’d like to find some really easy ones for young beginners (grades 2-4) and I’m having trouble finding any. The few places I’ve found puzzles represented as really easy, they are small and use small numbers, but still have way more ambiguity than I’m looking for. Many don’t even have a unique solution, which bothers me. What makes an easy Kakuro easy is having a few places where the digits can be easily reasoned out, and where filling in from there leads to a few more places where the digits can be easily reasoned out. A puzzle where large numbers intersect small numbers is generally easier than a puzzle that just uses all small numbers, because the possibilities at the intersection are often smaller when the magnitudes differ. I’m finding it so hard to find those that I’m thinking of trying to make my own. But so far I haven’t found good software to support me, and I certainly don’t feel like drawing them up by hand in Word or something. I’d really like something cheap and easy that checks that my puzzle has a unique solutions, and possibly even provides some kind of difficulty rating. If anyone knows of something that fills that bill (preferably free, though I don’t mind paying a reasonable amount for quality software), please let me know!
For those who want to play online, here are some options, listed from most basic to most fully-featured:
DoKakuro has a basic online solving widget, though they only offer 5 free puzzles before asking you to pay a small fee for 100 more. Their puzzles are the only ones I’ve seen where single-digit numbers are used, which I don’t like.
Kakuro.com has a nice online solving widget that shows you all the possible combinations for a given entry, if you don’t want to figure them out yourself. You only get access to one puzzle per day, unless you purchase their software (though they do have a trial version available for free).
KakuroPuzzle has a downloadable solving environment as well as printable puzzles; I haven’t tried the download though.
Kakuro.net also shows you the combinations if you request them, but doesn’t seem to have any method of “penciling in” multiple possibilities for a cell while you’re working. The site allows you to generate a large number of puzzles in three different sizes and three different difficulty levels.
Based on my initial experiences, I like KakuroConquest the best of those I’ve found so far. It has the easiest method for penciling-in that I’ve found — If you type more than one number in a cell, they shrink; when you erase all but one, it becomes the entry in the cell. They seem to have a large number of puzzles available at several difficulty levels as well. They also have a FaceBook applet, so you can challenge your friends.
