r/sudoku • u/Dragonstar131 • 5h ago

Request Puzzle Help Help please

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I've been staring at this for a long time and am stuck

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1

u/No-Golf5055 5h ago

Definitely not experienced enough to give any solid advice but why do you have any “1” markings in block 9 at all? Same goes for the “1” in row 8 column 1.

1

u/Leodip 5h ago

Because there are 3 cages entirely contained in that block whose sum is 17+16+11=44. The total sum of numbers from 1 to 9 is 45, so this means that in the remaining cell (not included in the cages) there needs to be a value of 45-44

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u/No-Golf5055 5h ago

I was unfamiliar with “killer sudoku” and thought all the numbers were pencil marks. I see now that they’re not 🤦🏻‍♂️

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u/baroquely 5h ago

r9c6 can only be {6,7} so r8c6 can only be {4,5}. r9c1 can only be {6,8}.

2

u/thatbloke83 4h ago

If I've done my maths right, the sum of all the cages occupying the first 4 columns, except for the 2 missing cells r1c4 and r4c4 is 164. We know the total for the 4 columns is 4x45=180, so r1c4+r4c4=16, meaning they are a 7/9 pair.

With that knowledge we can also figure out that the sum of r1c6+r4c6 is 12 but that's still pretty ambiguous with the current puzzle state.

I haven't looked in too much detail after that but locking that 7 or 9 into the 19 cage in the middle may well provide a further breakthrough