Since 2021, we have posted some extra difficult Sunday Stumpers, about once a month. These will be quite tough puzzles, but with a logical path to be found (and solution videos to help). This seventh Sunday Stumper of 2022 is a variation of Japanese Sums by John Bulten.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Yamato

Author/Opus: This is the 88th puzzle from our contributing puzzlemaster John Bulten.

Rules: Standard Japanese Sums rules: Place the numbers in the indicated range (1-9) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell. A ? can represent any sum of 1 or larger.

Also, all unused cells must form an unknown fleet of 1-cell wide ships in the grid. Each segment of a ship occupies a single cell, and ships do not touch each other, even diagonally.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 18:30, Master = 30:00, Expert = 1:00:00

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Why was 6 Afraid of 7?

Author/Opus: This is the 10th puzzle from guest contributor Sam Cappleman-Lynes.

Rules: Place the numbers in the indicated range (1-8) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell. A ? can represent any sum of 1 or larger.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 12:00, Master = 20:00, Expert = 40:00

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Twenty20 Vision

Author/Opus: This is the 238th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Place the numbers in the indicated range (1-9) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell. The adjacent question marks (??) show two-digit numbers, not two groups)

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 6:00, Master = 9:15, Expert = 18:30

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Doubles

Author/Opus: This is the 96th puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Place the numbers in the indicated range (1-6) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell.

Difficulty: 3.5 stars

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

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Common Denominations

Author/Opus: This is the 415th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Place the numbers in the indicated range (1-6) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:30, Master = 4:00, Expert = 8:00

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: 1 to 10

Author/Opus: This is the 372nd puzzle from our managing editor Serkan Yürekli.

Rules: Fill some cells with numbers 1-4 so that each row and column contains each number from 1 to 4 exactly once as well as two empty cells. Numbers outside of the grid indicate the sum of all numbers in the first connected group in that direction as in a Japanese Sums puzzle.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:00, Master = 3:15, Expert = 6:30

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: High Five

Author/Opus: This is the 50th puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Place the numbers in the indicated range (1-5) in some of the cells so that no number is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent number groups in that row or column, in order. Each sum is separated by at least one unused cell. A ? can represent any sum of 1 or larger.

Difficulty: 1 star

Time Standards (highlight to view): Grandmaster = 0:40, Master = 1:00, Expert = 2:00

Solution: PDF and solving video.

Note: Follow this link for other Japanese Sums puzzles.

Just released in our e-store is Grandmaster Puzzles Quarterly: Volume 4, our latest collection of original puzzles spanning multiple genres. This volume includes several familiar styles with the first extended section of Japanese Sums puzzles we’ve published, which will also be the style for this upcoming web week.

The full set of elegant and hand-crafted puzzles, coming from twenty-two of the world’s best puzzle designers, spans:

– 7 Even/Odd Sudoku and 4 Isodoku (Even/Odd)
– 7 Japanese Sums and 3 Easy as Japanese Sums
– 7 Minesweeper and 3 Minesweeper (Sudoku)
– 7 Nurikabe and 3 Nurikabe (Pairs)
– 7 Pentominous and 3 Pentominous (Cipher)
– 7 Castle Wall and 3 Castle Wall (Hex)

Our recent week of Balance Loop puzzles is gathered together in this PDF and the solutions are in this PDF. More Balance Loop puzzles (that are only in these books and not on our website) can be found in our e-store at this link.

The daily solution videos, this week from Prasanna, are on the posts and linked below:

Astute observers may have noticed that Japanese Sums was recently added to our Number Placement puzzle list on the main blog roster. We’ve also fully digitized the Penpa backlog for it. This upcoming week will feature this “new” puzzle to the website, as well as a Sunday Stumper next week. Japanese Sums will also be one of the six puzzle styles in Grandmaster Puzzles Quarterly 4 which will be released later today, so watch for more information on that.

(view directly for a larger image)

PDF

or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s)

Theme: Diamonds

Author/Opus: This is the 237th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Balance Loop rules. Also, number clues are not fully specified and must strictly follow the inequality values given.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 9:00, Master = 16:00, Expert = 32:00

Solution: PDF and solving video.

Note: Follow this link for other Balance Loop puzzles. If you are new to this puzzle type, here are our easiest Balance Loop Puzzles to get started on. More Balance Loops can be found in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli and in Balance Loop by Prasanna Seshadri and Murat Can Tonta.