PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: A Study in Scarlet

Author/Opus: This is the 543rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules.

Time Standards (highlight to view): Grandmaster = 4:45, Master = 8:15, Expert = 16:30

Solution: PDF and solving animation.

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More Sudoku including variations can be found in these books in our e-store. Also, visit this page to purchase all of the puzzles from the 16th World Sudoku Championship including classic Sudoku.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our The Twelve Days of Sudoku Discussion post on the GMPuzzles Discord.

Note 3: Please check lesson notes from Dr. Sudoku on Google Docs.

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Add to protect the innocent: gur ubhfr vg frrzf V nz jnyxvat gbjneqf vf abg zl ubhfr be ba gur fnzr fgerrg. V unq n zntvp zbzrag va gur cnex jvgu gur fbat “Ab Fhecevfrf” naq n fcrpvny guvat ybbxvat va guvf qverpgvba ba Ebhgr Svir.

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Note: All of these photos were taken on or around Dec. 28th when I was spending time in Boston area. Lots of familiar memories and some new ones, merging with different ideas on my brain around this time.