Medium sudoku 3

A medium nine by nine, which is the one most people mean by «a sudoku». There is always a next square you can prove, but finding it takes noticing that two cells in a box can only be two numbers between them — the point where scanning stops being enough.

7691478541735737829596432713584687
Show the answer key
578623491143789526296541837914357268637812954852964713389276145721435689465198372

What is on this sheet

Given numbers
34
Difficulty
Medium
Hardest step needed
Naked pair
Grid
9 × 9

About this puzzle

Medium means 30 to 35 given numbers, and at least one step that needs a pair or a locked candidate rather than plain scanning. The grid was solved technique by technique to grade it: if it had needed trial and error it would not have been published, and the single answer is printed on the second page.

This particular grid starts with 34 of the 81 numbers already printed, and the hardest technique it asks for is: Naked pair.

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