10
$\begingroup$

i) Hidden in this 8 x 8 board are the first 31 primes starting with 2 and up to to 127. They occupy adjacent, non-overlapping cells (up to 3), and are read horizontally (from left to right) or vertically (from top to bottom). Find them!

ii) Prepare a similar soup, but in a 10 x 10 board filled with the first 43 primes (2 to 191) such that these primes can be located uniquely inside the soup. Make it as hard as possible to identify primes!

enter image description here

Improve this question
$\endgroup$
2
  • 3
    $\begingroup$ This sounds like it should really be two separate questions $\endgroup$
    – fljx
    Commented Aug 13, 2023 at 16:16
  • 5
    $\begingroup$ Question 2 isn't too well defined, mainly because it's impossible to quantify how 'hard' puzzles are. Largest number of red herrings? $\endgroup$
    – new Q Open Wid
    Commented Aug 13, 2023 at 20:57

1 Answer 1

Reset to default
11
$\begingroup$

i)

You can look at the 0's in the grid to uniquely identify 101, 103, 107, 109. That gives us a good starting point and you can continue from the immediate surroundings to fill up the rest of the grid.

ii)

Starting from the original grid and tweaking it a bit:

 1138829711
 1113961178
 9794167291
 1109174711
 2771033155
 7310753317
 1019233159
 1377163543
 3173139191
 1149167137

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.