Dr. Sudoku Prescribes #3 – Sudoku

Missing Digit Sudoku by Thomas Snyder


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

Theme: Missing Digit? (opus 2); this avant-garde sudoku poses the question “Is there a 5 in the grid or not?” It is similar to an earlier work by Dr. Sudoku first displayed at the Silicon Valley Puzzle Festival where a different digit, 8, was missing in the same way.

Rules: Standard Sudoku rules.

Answer String: Enter the 1st column from top to bottom, followed by a comma, followed by the 4th column from top to bottom.

Time Standard: Sudoku Master = 4:00, Expert = 12:00, Novice = 40:00

Solution: PDF

Note: This puzzle may seem a bit hard for a Wednesday puzzle, but it is a fun, narrow solving path puzzle with a refreshing theme. The “Time Standard” at this site is used to tell you how hard a puzzle will be, even when the day of the week might be slightly off. 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 classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

  • tamz29 says:

    Couldn’t fill in a single cell until about 2 minutes in.

    • Avatar photo drsudoku says:

      I like making these classic sudoku with a first-step roadblock that is almost like a “Just One Cell Sudoku” to get started. I’m pretty sure there are only two spots you could have put in your first digit; they are very close to each other and will be the first two numbers all logical solvers likely fill in.

      • >> I’m pretty sure there are only two spots you could have put in your first digit; they are very close to each other and will be the first two numbers all logical solvers likely fill in.

        hmmm, that doesn’t jive with my solving experience… the first two digits I filled in were the 1 in the lower right box, and the 3 in the middle left box.
        (I hope that’s vague enough not to give anything away… is there a html tag for secreting stuff available?). At any rate, I enjoyed the break-in that I found, and it didn’t take too long to find it.

        I didn’t time myself, but I’m pretty sure I was well under the expert time, and probably just above the master time.

        • Avatar photo drsudoku says:

          True. I’ll have to amending my statement to allow a third option in the lower-right, which is actually a reasonable first find in a digit-focused world.

          I’ll figure out some kind of spoiler tagging system to my list of things to do.

  • greenhorn says:

    Another nice puzzle. It took me 3 minutes and 18 seconds. Now I have 10 fives in the grid.

  • Fred76 says:

    Just the difficulty I like: a few things to see, not too hard, but not very easy to spot.

  • Rishi Puri says:


    nice puzzle. the digit 1 was a cool starting point and then everything just kind of fell into place.

  • skynet says:

    8 mins 18 sec.Love this sudoku and i filled the digits just in those 2 spots that you refer to motris.I found them very early but slowed down in the middle..Maybe i should improve on my notations…and i like the way when ucategorize based on the times…very good idea…would love to know where i stand based on the benchmark

  • Trayton says:

    Brutal puzzle for me; broke it once 13 minutes in. Second try took 42 minutes including a bifurcation after placing 4-5 digits. I eventually found the 1 in the lower right (as David mentioned) which unleashed the rest of the puzzle for me. In hindsight, I see how placing the one could’ve precluded my guessing.

    For me, this would be a good puzzle for a walkthrough to show higher-level patterns to solve sudoku.

    • Avatar photo drsudoku says:

      Besides the 1 in the lower-right, there are LOTS of pairs to mark in the left three columns. These form pointing pair situations that should let you get some things placed on that side.

  • skynet says:

    and btw where should i post the answers?!

    • Avatar photo drsudoku says:

      At the bottom of the post you should see a FAVE/SOLVED button. If you want to log having solved the puzzle and earn credit in the future when I have contest drawings or anything else, click SOLVED and type in the two strings. If you are not interested in doing this, then just enjoy the puzzles and ignore the entry row.

      • Avatar photo drsudoku says:

        I’ll add you have to be logged in to Dave Millar’s system, but the buttons should make registering really easy right now. Reply here if you have problems.

  • skynet says:

    Hi motris i dont see any FAVE/SOLVED button.Immediately after the editorial note i see the comments posted

    • Avatar photo drsudoku says:

      This is what the bottom of my posts looks like to me so you see what I mean on the right side. Can you share your browser/OS so I can look into troubleshooting this? Do you know if you normally block certain types of external code on web pages?

  • skynet says:

    Thnks i m able to get it now…i logged in through my office system earlier which has some web filter..maybe it blocked or something…not too sure abt the java stuff..i can see fav /solve button on my pc

  • Ours brun says:


    Nice one, with an interesting solving path. Quite hard, but never offering the temptation to guess. The kind of quality classic sudokus I hope to see in China in a few months.

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