4x4 Prime Cages Sudoku
(Published on 6. July 2020, 17:24 by DiMono)
Standard 4x4 Sudoku rules apply.
Each cage adds up to a unique prime number. You may repeat digits in a cage.
Solution code: Row 1, Column 2, Row 4
Comments
on 1. December 2021, 22:00 by abecede
Lovely little thing. Thank you DiMono! My only problem was penpa, so I created a penpa+ version (with answer check) where typing in numbers is also a lot more user friendly. See https://git.io/JMoD6
on 15. October 2020, 17:07 by Willy Wonka
A 3 star difficultly puzzle for me... until I read the rules again and found the word "unique"! A very lovely little puzzle
@Willy Wonka Thanks for taking it on!
on 13. August 2020, 16:14 by wkossen
lovely puzzle. took me a while to get my head around how to solve it. should have a higher rating!
on 31. July 2020, 02:14 by SudokuExplorer
@uvo I strongly agree with you. Especially when you want to talk about unique prime factorisation. I would consider 1 (and -1) to be the units of the ring of integers.
on 31. July 2020, 00:20 by uvo
1 is not a prime. Any "definition" that says otherwise is wrong.
on 30. July 2020, 23:48 by Naantje
It's probably best to mention in the rules that you don't consider 1 a prime number, because according to some definitions 1 does qualify as a prime. (Oh, the debates I've had over the years!) At least two possible solutions if you consider 1 a prime.
@Naantje A prime number is defined as having exactly two divisors: 1 and itself. The number 1 only has 1 divisor. Therefor, by definition, 1 is not prime. It has nothing to do with my opinion, it is objective fact.
@DiMono: By the definition you were taught, but not everyone is taught that definition, some people aren't taught the "exactly two divisors" part... I think by this point it's pretty clear that many people are making the mistake of counting 1 as prime and it's not a logic problem, it's a problem of unclear definitions. I remember several teachers who included 1 on the list of primes... I just think clarification in the rules would make the puzzle more enjoyable.
on 14. July 2020, 02:57 by DiMono
I suspect one reason for the difficulty being rated 1-star is the simple fact that it is a 4x4 puzzle. 4x4 puzzles are by their nature significantly easier than their larger counterparts, so it's not unexpected for any 4x4 to have an easier rating by consensus, regardless of how hard it is compared to other 4x4 grids.
Personally, I think it's a 2-star 4x4 puzzle, but the setter does not get to decide how hard the solvers find it. It is what it is. :)
on 13. July 2020, 23:53 by glum_hippo
There are comments where people reveal that they got tripped up by some of the rules, but that’s not the same as having difficulty. The rating system involves a heavy amount of subjectivity. For my part, even if I struggle with a puzzle I might give it an ‘easy’ rating if, in retrospect, the logic seems fairly straightforward.
on 13. July 2020, 23:21 by uvo
"Wrong" implies there is an objective "Right", which I don't think is true at all.
on 13. July 2020, 23:17 by henrypijames
@uvo: I understand the mechanism. I'm saying judging by additional empirical data, those 1 star votes are wrong.
on 13. July 2020, 11:55 by uvo
The difficulty is calculated simply as average of everyone's votes. If it is shown as one star then because enough solvers voted one star.
(There is some bias because someone who didn't solve a puzzle is not eligible to vote, but I don't think that makes much of a difference in this puzzle.)
on 11. July 2020, 14:44 by henrypijames
Not only is this puzzle underrated, but the difficulty level should be higher than 1 star as well, considering how many people are admitting to not being able to solve it straightforwardly (myself included).
on 11. July 2020, 01:55 by DiMono
Updated German text to be more clear.
on 11. July 2020, 00:12 by glum_hippo
Oder 'eine verschiedene Primzahl' perhaps
on 10. July 2020, 23:35 by olima
Please clarify in the German version that every killer sum appears only once (which seems to be the intention, right?). (Jeder Käfig ergibt eine nur einmal vorkommende Primzahl als Summe.)
I didn't realize the German was not descriptive enough. I have updated the text. Thank you for bringing it to my attention.
on 10. July 2020, 21:14 by glum_hippo
1 is not a prime number. The prime numbers that could possibly appear in this puzzle are the following: 2,3,5,7,11,13,17
on 8. July 2020, 22:46 by SKORP17
Ich bin auch darüber gestolpert, es gibt eine Zahl, bei der man nicht denkt, dass es eine Primzahl ist.
on 8. July 2020, 19:38 by Saskia
Thanks a lot! Have to try again :-)
on 8. July 2020, 19:12 by henrypijames
I agree: This puzzle absolutely deserve a higher rating - so simple yet so pure its logical path.
on 8. July 2020, 14:49 by ffricke
Sehr schöne Idee
on 7. July 2020, 19:24 by Rollo
@Saskia: Nein. Du hast zwei gleiche Primzahlen.
on 6. July 2020, 22:35 by uvo
Die schlechte Bewertung kann ich überhaupt nicht nachvollziehen.
