You are a special consultant who is brought in only for the toughest of cases. A serial killer has been on the loose and has struck the first day of the month for three months in a row now. Interpol needs your help to find the perpetrator and bring him to justice. Your job is to compile the evidence that the police have gathered and figure out his 81-digit Galactic Positioning Number. Once we have that, there'll be nowhere he can hide from the long claw of the law.

The GPS number is displayed on a 9 by 9 grid and is read left to right, top to bottom. The grids must be in compliance with all of the following rules:

  • Each row, column, and cell of nine must contain the numbers 1 through nine with no duplicates.
  • The sum of the digits in each colored region must equal the value denoted in that region.
  • This largely follows the rules of Killer Sudoku, with the exception that a number can occur more than once within a single colored region.

In this case, we know that all three of the grids will have the same solution. Due to budget cuts, some regions have unknown sums.

Exhibit A:

I'm fucking bad at math twice

Exhibit B:

The second grid

Exhibit C:

The third grid

For your final report to be accepted, you need to provide the completed grid in a image before the killer strikes again, January 1st. Good luck.

Blank report

Hint: This hint combines the three puzzles above into a single grid with an identical solution. If you like the challenge of cross-referencing grids, don't use the hint below.

The cells adjacent to each numbered intersection must add up to the sum shown. The puzzle otherwise followed standard sudoku rules. The answer to this sudoku should be identical to the challenge above.
parent puzzle

  • $\begingroup$ Just checking if there is a typo in A because rot13 (n fvzcyr fhz bs bar-gb-frira nyernql lvryqf gjragl-rvtug, znxvat gjragl-fvk vzcbffvoyr sbe xvyyre fhqbxh jvgu havdhr ahzoref) Edit: Forgot that it is rot13(pebff-tevq) so it still holds $\endgroup$
    – Kryesec
    Dec 2, 2018 at 3:34
  • $\begingroup$ As a note, there isn't a cipher, you just need to solve the sudoku. $\endgroup$
    – Arpeggio
    Dec 2, 2018 at 3:59
  • 1
    $\begingroup$ @Kryesec - "This largely follows the rules of Killer Sudoku, with the exception that a number can occur more than once within a single colored region." $\endgroup$
    – aivirai
    Dec 2, 2018 at 12:52
  • 1
    $\begingroup$ Just noticed an error: A4+A6+A10 should be equal to 90, but it isnt! Thanks $\endgroup$ Dec 6, 2018 at 10:20
  • $\begingroup$ Please refer to my answer for the notation $\endgroup$ Dec 6, 2018 at 10:22

1 Answer 1




For convenience, I will call the pieces according to the following notation:

Exhibit A:


Exhibit B:


Exhibit C:


Also, (c,r) represents a grid, where c represents column from left to right, and r represents row from top to bottom.



From A16 and B15,


C17=24=[7,8,9], A1=24=[7,8,9]




From B6 and C2,









  • $\begingroup$ Could anyone help me scale down the notations a bit (I don't know how) as the answer may be too long? Thank you! $\endgroup$ Dec 3, 2018 at 0:03
  • 2
    $\begingroup$ I think a useful approach may be to use an online sudoku maker, start with all candidate numbers, and then eliminate numbers as you make progress. Alternatively, you can put the four images I provided into an image editing software as independent layers. That may help with visualization of the space relations. $\endgroup$
    – Arpeggio
    Dec 3, 2018 at 0:23

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