ditto Inge; 16 was most to get logically w/out guessing
Difficulty score 51. No green.
Like gman, I found 16 no problem. Then instead of guessing, I found a logical impossibility (start with an assumption and show that it leads to a duplicate digit in one of the rows, columns or blocks and hence the assumption is incorrect). I found 2 digits that way and then everything fell into place. Sounds almost the same as guessing, except I was looking ahead instead of filling in the grid until I got into trouble.
I solve using only logic. What's the point of guessing? Any chimpanzee can guess and will eventually stumble upon the correct solution, oo-oo-o-o-ah-ah-ee-ee. What about the dng part? Well, good on ya if you can solve logically and use no greens, but if you use reds then you're lying by omission. Occasionally I need greens because my brain's tired. I'm as old as dirt. There's no shame in greens. The young brains can do the greens by rote, committing them to memory. Technically they still use them, they just don't write them down, LOL.
BTW I solved this rather quickly using logic and I didn't need any difficult techniques. Couple of pointing pairs and it cracked like an egg.
Jackt: the puzzle is an expert. That means it requires the application of 1 or more techniques more advanced than pointing pairs to solve by logic. You may have found a correct solution by incorrect logic if pointing pairs were the most advanced technique you used.
I found the 16.. so greening up
terminate.. used one guess. back to the sudoku solver to see how I should've solved this without guessing...
finished ... one guess was all it took ... fun puzzle
done, no greens
Couldn't do it with pointing pairs - have always used that technique but never knew it was called that so had to look it up - used a guess and greens