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24 December 2010 @ 12:45 am
Friday Puzzle #81 - a 12/24 TomTom  
This year saw the release of my unique take on KenKen(TM)/Calcu-doku puzzles: the book TomTom Puzzles. "Humanizing" calcu-doku puzzles, by creating more interesting puzzles to look at, as well as more interesting puzzles to solve, has been a real signature of my recent construction. I explored many types of visual themes for these puzzles, and one of the common ones not involving region shapes is having just one or two clue values repeated throughout the puzzle. For example, I made a 24/7 puzzle that was fit to be solved any time on any day, and a "Dirty Dozen" puzzle with exactly twelve 12s and no other clues.

Today's date is a really good one for making another themed challenge using just 12 and 24. This puzzle is a bit hard, but if no one has a walk-through posted in the comments by this weekend, I'll start putting up some hints to get started. Happy Puzzling!

Rules: Enter a digit from 1 to 8 into each cell so that no number repeats in any row or column. The number in the upper-left of each bolded cage must equal the value of a mathematical operation (+ or x) applied to all the digits in the cage. Digits can repeat in a cage, provided they don't repeat in a row/column.

TH: pencilrpipuzzleguy on December 24th, 2010 02:41 pm (UTC)
Nice puzzle; didn't find it all that tough. Do you really want someone to spell out all the steps?
motrismotris on December 24th, 2010 07:02 pm (UTC)
Glad you liked it. I've never had a good TomTom difficulty calibration, having never solved any myself, but I'd certainly say you are a much better than average solver for the audience I get coming to my calcu-doku.
TH: pencilrpipuzzleguy on December 24th, 2010 08:08 pm (UTC)
Fair enough. I note that my question may have sounded sarcastic; I did not intend it as such.
(Anonymous) on December 24th, 2010 09:03 pm (UTC)
Indeed, not an easy one, but not very difficult though. A few tricks quickly noticed, and it fell. Of course, I guess someone with no experience of solving this kind of puzzle would find it pretty hard ; but are there lots of beginners amongst your followers ?

motrismotris on December 26th, 2010 06:43 pm (UTC)
Well, the thing is I'm now cross-posting every week on wired.com which will have a more general audience. Indeed a solver there had trouble but the comments should help them out. I also post answers over there specifically for that purpose.
Robert Hutchinsonertchin on December 25th, 2010 11:34 am (UTC)
Found this one challenging but not brain-busting--solved it on my computer in (checks timestamp) about 20 minutes. I did feel that this one played to several of my TomTom strengths, mainly figuring out which sets of numbers have to go in which cages along an entire row. (And 12+24 is a good number to refer back to often.)

I don't have the energy at the moment to do a breakdown, but the top two rows, rightmost two columns, and the big 12 cage is where one ought to start working, I believe.
(Anonymous) on December 25th, 2010 08:10 pm (UTC)
Hint walk-through:
Hint walk-through:

Didn't find it difficult at all. Took much longer than it could
have, since I kept notes, and tried to keep them not explicit.

There were very few cages where I had to really think if it was
a sum or a multiplication.

A helpful fact is that 12+24=1+2+3+4+5+6+7+8.

bottom row - sets
top row - sets (unordered)
large 12 top left - specifically the not-third row cells
right col - options
row 2 - sets (unordered) place right val
12 on left - place vals
24 in 37-47 - place vals
right corners (and 17)
square 24 vals by rows -
24 at 26-27 - place vals
place val at 87
place 77
finish right col (see long 24 in row 5)
place vals for 12 in row 5-6 (long 24 again)
finish col 5 (same)
place 1s in right half of board
24 on row 5 (vals)
square 24 (vals)
the rest falls quickly
motrismotris on December 26th, 2010 06:41 pm (UTC)
Re: Hint walk-through:
Thanks. This captures what I would have mentioned, and did add on wired.com where this post also went.

As you say, the numbers add up to 36 (or 12+24, to fit the theme), with the top and bottom rows and also the right column having unique sets of values to figure out. The puzzle then solves by focusing on rows 2,3,4 and working downwards, certainly taking advantage of the large 12 cage that has only one set of values.