Merch Informer Alternatives for Amazon Merch Sellers
No single tool wins for every Amazon Merch seller. Alternatives sorted by the job you need done: niche research, trademark screeni…
What a Number Fill-In Puzzle Is (and What It Is Not)
A number fill-in is a crossword with no clues: a grid of white and black squares and a list of numbers sorted by length. Every number goes into exactly one slot, across or down, and digits must agree where slots cross. The opening move is always the length group with a single number, or a printed starter digit.
The phrase "number fill" gets used for at least three different puzzle mechanics, so know which one you are shopping for before you pick a tool.
| Puzzle | Grid | Cells hold | Clues come from | Typical buyer |
|---|---|---|---|---|
| Number fill-in (crossword-style) | Crossword shape, 9×9 to 21×21 | One digit; slots 3–7 digits long | Number bank sorted by length, often one starter | Adults and seniors who like crosswords but not trivia |
| Word fill-in | Same shape | One letter | Word bank sorted by length | Same audience; the larger genre by Amazon listing count |
| Number search | Solid grid, 12×12 to 20×20 | Every cell pre-filled | Target numbers hidden in eight directions | Word-search fans wanting a change |
| Sudoku | 9×9 grid with 3×3 boxes | Digits 1–9, some given | Row, column and box logic; no bank | Everyone; the most crowded shelf on Amazon |
| Latin square (Octozia's "Number Fill") | Solid 5×5, 7×7 or 9×9, no boxes | Digits 1–N, some given | Each row and column holds 1–N exactly once | Sudoku buyers wanting a lighter puzzle; kids' logic books |
Check the last row before you buy software: Octozia's KDP Creator book type labelled Number Fill produces Latin squares, not the crossword-style fill-in with a number bank that dominates search results for this term. Both genres sell on KDP to overlapping but not identical buyers, and only one currently comes out of Octozia.
A Solved Example You Can Check by Hand
Here is a 5×5 crossword-style number fill-in: six numbers, three across slots (rows 1, 3, 5) and three down (columns 1, 3, 5); ■ marks a black square. The table below is the solved grid; picture the digits removed and only the bank given.
Number bank. 3 digits: 272, 312, 471. 4 digits: 4268. 5 digits: 18503, 63592.
Solve order: 4268 is the only 4-digit number, so it must fill the only 4-cell slot (column 1). That fixes a 6 at the start of row 3, so row 3 reads 63592. Its middle digit, 5, lands in column 3, so column 3 reads 18503. Column 3 starts with 1, so row 1 ends in 1: that is 471. Row 5 starts with the 3 sitting at the bottom of column 3: that is 312. The one number left, 272, is column 5.
| Row | Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
|---|---|---|---|---|---|
| 1 | 4 | 7 | 1 | ■ | ■ |
| 2 | 2 | ■ | 8 | ■ | ■ |
| 3 | 6 | 3 | 5 | 9 | 2 |
| 4 | 8 | ■ | 0 | ■ | 7 |
| 5 | ■ | ■ | 3 | 1 | 2 |
The step everyone gets stuck on is uniqueness. An earlier version of this grid used a 3-cell slot in column 1 holding 426 instead of the 4-cell 4268, and it had two valid solutions: swap the two 5-digit numbers and the two remaining 3-digit numbers re-pair correctly, because 426 and 471 share a first digit and 272 and 312 share a last digit. Random digit strings create that kind of symmetry more often than you would expect, so any generator you rely on for resale needs to run a solver and reject grids with more than one answer, not just print whatever it first assembles.
Just want a few puzzles to print for a classroom or a family game night? The free pack above covers that: ten ready-made number fill-ins across three difficulty levels, answer keys included, no account needed. Its licence covers personal and classroom printing only — it is not the same as generating your own batch for a book you plan to sell, which is the commercial workflow the rest of this page covers.
Generating Number Fill Pages in Octozia KDP Creator
KDP Creator is a web app inside the Octozia dashboard and it is not free: every plan starts with a 3-day trial that requires a card up front, and you can cancel any time before the trial ends. As of September 2026 it prices at $9.99 a month, $99.99 a year, or $79.99 once for a lifetime plan; check octozia.com/pricing for the current numbers.
| Setting | Options in the panel | What it changes |
|---|---|---|
| Difficulty | Easy (5×5), Medium (7×7), Hard (9×9) | Grid size and difficulty move together; more given digits on Easy, fewer on Hard |
| Trim size | 5×8, 5.5×8.5, 6×9, 8.5×11 in | 300 DPI page images with a fixed 0.625-inch margin on every side — Octozia's own setting, not a KDP minimum |
| Page count | Number of puzzles, 10–200, capped by your plan tier | One puzzle page plus one solution page per puzzle, plus front matter |
| Seed | Randomised per book | Two runs with identical settings still produce different puzzles; per-puzzle fingerprints are written to the manifest |
| Output | ZIP of numbered PNGs plus a manifest file | No PDF is generated — you place the pages in order in your own PDF tool to build the KDP interior |
1
Pick Number Fill
Open KDP Creator in the dashboard and choose the Number Fill card among the five default puzzle types (Sudoku, Word Search, Maze, Math and Number Fill).
2
Set difficulty and trim
Match grid size to trim: a 9×9 Hard grid needs more room per cell than a 5×5 Easy grid at the same trim, so check the formatting table below before committing to Hard on a small trim.
3
Type the puzzle count
Enter how many puzzles you want, up to your plan's daily cap. Each puzzle gets its own solution page later in the file, roughly doubling the page count you might expect from the puzzle count alone.
4
Generate and download
The app builds the puzzles from a server-issued seed and hands you a ZIP. Import the numbered PNGs into your interior document in order, add a gutter margin for your final page count if needed, and export the interior PDF yourself.
Daily generation limits are set by plan and can change, so treat the caps shown on screen as current: a 3-day card trial allows fewer books and pages per day than a paid or lifetime plan, so do not plan on finishing a full 200-page book during the trial window.
How to Build Classic Number Fill-Ins Yourself
For the crossword-style fill-in with a number bank, Octozia has no generator, but a spreadsheet will get you a batch, since any digit can sit in any cell without the row/column constraint a Latin square needs. Copy the black-square layout of a published 13×13 fill-in, keeping every slot at least 3 cells long, 30–45 slots total. Put =RANDBETWEEN(1,9) in each slot's first cell and =RANDBETWEEN(0,9) in the rest so no number starts with zero, then read each slot off, group by length, sort ascending, and regenerate any duplicate. Check for a second solution by swapping equal-length numbers that share crossing digits; if the swap still fits, change a digit and recheck. Keep one length group to a single entry, or print a starter digit, so the solver has a way in. At roughly 20–30 minutes per puzzle, a 100-puzzle book is close to a week of evenings by hand. Puzzle Maker Pro sells a dedicated number fill-in module — check its current product page for a single-solution guarantee before you rely on it for resale — and is the faster route for more than one title in this genre. Octozia does not currently make this puzzle type, only the Latin-square version.
Print-Ready Formatting for KDP
Puzzle books are almost always black-and-white, no-bleed interiors, which is the cheapest printing category and allows the smallest margins. KDP paperbacks run from 24 to 828 pages; anything wider than 6.12 inches or taller than 9 inches counts as a large trim and costs more per page to print. The margin figures below are Amazon's stated requirements as of September 2026 — confirm them on KDP's own margins page before you upload, since Amazon has adjusted them before.
| Page count | Minimum inside (gutter) margin | Minimum outside margin, no bleed | Octozia's fixed 0.625 in margin |
|---|---|---|---|
| 24–150 | 0.375 in | 0.25 in | Clears it easily |
| 151–300 | 0.5 in | 0.25 in | Clears it; a 100-puzzle run with solution pages (about 200 pages) lands here |
| 301–500 | 0.625 in | 0.25 in | Sits exactly at the minimum; a near-cap book (close to 200 puzzles, ~400+ total pages once solution pages are added) lands in this band |
| 501–700 | 0.75 in | 0.25 in | Above Octozia's per-book page cap — merge two exported runs and add gutter yourself |
| 701–828 | 0.875 in | 0.25 in | Above Octozia's per-book page cap — merge exported runs and add gutter yourself |
Trim Size for Number Puzzles
| Trim | Usable width at 0.75 in margins | Approx. 13×13 cell size | Best for |
|---|---|---|---|
| 8.5×11 | 7.0 in | About 0.54 in | Large print; number bank runs beside the grid |
| 6×9 | 4.5 in | About 0.35 in | Travel-size editions; number bank runs under the grid |
| 5.5×8.5 | 4.0 in | About 0.31 in | Pocket editions, best kept to 11×11 or smaller |
| 5×8 | 3.5 in | About 0.27 in | Too tight for 13×13; fine for Octozia's Latin squares up to 7×7 |
Only claim KDP's large-print category if body text runs 16 points or larger. A 13×13 grid on 8.5×11 clears that for the digits themselves, but an undersized number bank in 10–11 point type does not — check the bank's own font size, not just the grid. Put solutions at the back, several grids to a page, so a buyer checking one answer does not see the next puzzle's; see the interior templates by trim size for layout examples across all five puzzle types.
Build a 100-Puzzle Book in One Session
A hundred puzzles is roughly what buyers expect from a full-price adult puzzle book. A classic crossword-style fill-in built by hand might budget 4 front-matter pages, 100 puzzle pages, 25 solution pages at four grids per page and 1 blank: 130 pages, inside the cheapest gutter band.
Octozia's math differs. Every generated puzzle gets its own full solution page rather than a shared section, so a 100-puzzle Octozia book runs 100 puzzle pages, 100 solution pages and roughly 2 front-matter pages: about 202 pages. That crosses into the 151–300 gutter band, whose 0.5-inch minimum sits comfortably inside the 0.625-inch margin baked into every Octozia page, so no manual gutter fix is needed. Difficulty and grid size are tied together in the settings, so mixing difficulty (easier early puzzles, harder later ones) means running the generator more than once and combining exports in your own interior file, with the puzzle number printed into each page image to keep the sequence straight.
The extra solution pages cost more to print. On a large trim like 8.5×11, KDP's formula (September 2026 — check the current rate on KDP's printing-cost page) runs roughly $1.00 plus $0.017 per page for 110–828-page black-and-white books, so a 202-page Octozia interior costs about $1.00 + 202 × $0.017 = $4.43 against roughly $3.21 for a 130-page hand-built book with a shared solutions section. Budget that difference into your price.
Pricing and Niche Reality on Amazon
Number fill-ins are a small niche next to sudoku and word search, which is the appeal: fewer competing listings, and a buyer who finishes volume 1 tends to come back for volume 2. Real listings currently on Amazon in this niche include the titles below, checked by name in September 2026 — not a live price-and-rating pull, because star ratings, review counts and prices on small-press puzzle books shift often enough (sometimes within the same week on the same listing) that printing a specific number here would be stale before you read it.
| Listing (title, author) | Puzzle count stated on the cover | Stated format |
|---|---|---|
| Number Fill-Ins Large Print: 200+ Puzzles for Adults, Vol. 2 — Travis Davis | 200+ | Large print |
| Number Fill In Puzzle Book for Adults and Teens: 500 Large Print Number Fill Ins — The Puzzle Vibe | 500 | Large print |
| Number Fill In Puzzles: 120 Large Print Fill-In Puzzle Book with Starter Numbers — Relaxable Day | 120 | Large print, starter numbers given |
| Number Fill in Puzzle Book For Adults: 100 Large Print Number Fill In Puzzles With Starter Numbers — M R N Publication | 100 | Large print, starter numbers given |
| The Book of Number Fill-Ins: 500 Puzzles, Large Print — Djape | 500 | Large print |
Two patterns hold regardless of the exact price on any given day. Every listing above is "large print," which on a genre this text-light usually means an 8.5×11 trim, though the listing rarely states trim size outright — check the product dimensions field on the detail page before you copy a format. And the cover-stated puzzle count is not the final page count once you add solutions and front matter, which is the printing-cost gap the next table works through. For current price, star rating, review count and Best Sellers Rank on any of these, or a listing you are considering as a comp, open the live product page yourself and treat anything printed here as a starting point, not a snapshot.
KDP royalty on Amazon marketplaces is 60% of list price minus the printing cost, or 40% of list price for copies sold through Expanded Distribution (bookstores and other retailers); check KDP's royalty help page for the current terms before you price, since the printing-cost side of the formula changes independently of the rate.
| Trim | Pages | List price | Printing cost (Sept 2026 formula — verify) | Royalty at 60%, Amazon marketplace |
|---|---|---|---|---|
| 8.5×11 (large trim) | 130 | $7.99 | $3.21 | $1.58 |
| 8.5×11 (large trim) | 130 | $8.99 | $3.21 | $2.18 |
| 8.5×11 (large trim) | 130 | $9.99 | $3.21 | $2.78 |
| 8.5×11 (large trim) | 130 | $10.99 | $3.21 | $3.38 |
| 6×9 (regular trim) | 130 | $7.99 | $2.56 | $2.23 |
| 8.5×11 (large trim) | 130 | $6.99 | $3.21 | $0.98 |
Printing costs above use KDP's September 2026 formula — recompute with the current rate on KDP's own printing-cost page before you rely on these figures.
At the same list price, the smaller regular-trim 6×9 book nets more per copy than 8.5×11, because it costs less to print, not because of any rate change — the royalty rate is flat at 60% across this whole price range, only the printing-cost deduction moves. Large print sells at a premium partly because it needs the pricier trim to earn a comparable margin; if your audience does not specifically need large print, 6×9 is the better default for margin. Run your own numbers on the KDP royalty calculator, free with no signup, before you set a final price.
Title, Subtitle and Backend Keyword Ideas
- Number Fill-In Puzzles for Adults: 100 Large Print Puzzles with Solutions (Volume 1)
- Large Print Number Fill-Ins for Seniors: Easy to Hard Crossword-Style Number Puzzles
- Backend keyword ideas: number fill in puzzles for adults large print; fill in crossword number puzzles; number puzzles for seniors brain games
KDP gives you seven backend keyword fields; do not repeat title words in them or use another publisher's brand name. "Number fill-ins" is generic vocabulary, but some puzzle-magazine publishers hold marks on specific series names, so run any series title you plan to reuse across volumes through a USPTO trademark check first. Not legal advice; last checked September 2026.
Generator Comparison: Octozia, Book Bolt, Puzzle Maker Pro and Free Tools
Several tools make number puzzles for KDP; as of September 2026, only one on this list makes the crossword-style fill-in with a number bank. Prices below are list prices — check each vendor's current pricing page before you buy, since all of them change tiers periodically.
| Tool | Price (verify current) | Number puzzle it makes | Whole-book export | KDP trim presets | Uniqueness check |
|---|---|---|---|---|---|
| Octozia KDP Creator | $9.99/mo, $99.99/yr, $79.99 lifetime; 3-day card-required trial | Latin square 5×5–9×9, plus sudoku, word search, maze and math | ZIP of PNGs per run; you assemble the PDF | 5×8, 5.5×8.5, 6×9, 8.5×11 | Randomised seed with per-puzzle fingerprint; no documented single-solution solver on Number Fill |
| Book Bolt | Pro and Premium tiers, roughly $20–$36/mo depending on annual vs monthly billing — check bookbolt.io/pricing | Sudoku, number search and others; check current catalog for a dedicated number fill-in module | Yes | Yes | Not documented publicly; test a batch before committing |
| Puzzle Maker Pro (Windows) | One-time price per module — check the vendor site | Dedicated number fill-in module with a number bank | Batch to PDF or images | Manual page size setup | Check the vendor's current product page for a single-solution guarantee |
| Free web puzzle makers | $0 | Rarely offer number fill-ins specifically; mostly sudoku, word search or maze | Usually one puzzle at a time | Rarely; typically letter or A4 | Rarely documented |
A hobbyist printing a handful of puzzles for a relative is well served by a free web tool or the spreadsheet method above; read the licence either way, since free to use is often not free to resell from. Selling a crossword-style number fill-in book points you at Puzzle Maker Pro today, the only entry here with a dedicated number-bank module and a documented uniqueness check. Octozia fits better once you also need sudoku, word search and maze puzzles from one account with one seed system, and its lifetime price undercuts Book Bolt's ongoing subscription over time; the Book Bolt alternative breakdown goes deeper on that comparison. Neither Octozia nor Book Bolt currently generates the crossword-style number fill-in — worth knowing before you commit to either for this genre.
FAQ
Can I sell generated number fill-in puzzles on KDP?
Yes, as long as the tool's licence allows commercial resale and the puzzles are your own generated output rather than copies from a published magazine. Amazon rejects books that duplicate existing listings, so never reuse the same generated batch across two books. Read the licence agreement for whichever tool you use before you publish rather than assuming resale is included by default.
How many puzzles should a number fill-in book have?
Most full-price adult books on Amazon run 100 to 200 puzzles, which lands around 130 to 400 pages once you add solutions and front matter, depending on how solutions are laid out. Under about 60 puzzles tends to read as thin at a full-price point. A cheaper entry-level title can work with 50 puzzles at a smaller trim and a lower price.
What cell size do I need for a large-print number puzzle?
Aim for cells of at least roughly 0.5 inches so digits print near 20 points or larger. On 8.5×11 that generally keeps you to a 13×13 grid or smaller; a 15×15 grid drops cell size close to the edge of readable large print. On 6×9, only smaller grids reach that cell size, so most genuine large-print books stay on 8.5×11.
Are generated number fill-ins guaranteed to have a single solution?
Only if the generator specifically runs a solver and rejects any grid with more than one valid answer — plenty of generators, including hand-built spreadsheet methods, do not do this by default. Octozia's Number Fill puzzles use a randomised seed with per-puzzle fingerprints but do not document a single-solution solver, so spot-check a sample before you publish a batch at scale; the printed solution is always at least one valid completion.
Number fill-in vs fill-in crossword: which sells better?
Word fill-ins appear to have the larger audience on Amazon by listing count, likely because they draw in crossword buyers directly, but that also means more titles competing for the same search terms. Number fill-ins see fewer competing listings but a smaller pool of dedicated buyers. Publishing one title of each and watching which earns a second volume first is a reasonable way to test your specific audience.
Is a number fill puzzle generator the same as a lucky-numbers or 4-number-combinations generator?
No. Lucky-number and combination generators produce random lottery-style digit sets and have nothing to do with logic puzzles; a plain spreadsheet formula like RANDBETWEEN does that job in seconds. A puzzle generator, done properly, builds a grid and a number bank together and checks that the two fit in exactly one way before handing you a finished puzzle.
Generate Latin-square number puzzle pages at KDP trim size
KDP Creator renders 300 DPI puzzle and solution page images for trims from 5×8 to 8.5×11, seeded per book, and you assemble the interior PDF yourself. 3-day trial, card required, cancel any time before it ends.
