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Prime Sum Sudoku
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Posted on: Wed Jan 06, 2021 7:15 pm

Posts: 33
Joined: Fri Nov 01, 2019 9:33 pm
Prime Sum Sudoku
This one's a bit more challenging, but the rules are still simple. The clues hint at both which cells contain primes, and when sums of entries are prime. More info, a solution, and a PDF version at the following link:

Posted on: Thu Jan 07, 2021 5:08 pm

Posts: 300
Joined: Fri Jun 17, 2011 8:15 pm
Re: Prime Sum Sudoku
This is pretty clever. I haven't given it a lot of thought but it seems to have its own solving strategies.
If a 2-circle implies that one of the cells must be 2 since its the only even prime.
Similarly, a 0-circle implies that one of the cells must be 9 since its the only odd composite number less than 10.

Posted on: Thu Feb 25, 2021 7:39 pm

Posts: 33
Joined: Fri Nov 01, 2019 9:33 pm
Re: Prime Sum Sudoku
Thanks for the compliment! Yes, there's definitely some new tricks I needed to come up with to make and solve these. One interesting tidbit, is that I couldn't do the same sort of thing for differences at all (without getting tons of extra unwanted solutions.) There's a delicate balance that allows a single solution to sneak out in this sum case.

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