Sudoku
9 × 9 · Medium
Write 1 to 9 once in every row, every column and every 3 by 3 box.
Created for free at puzzleandprint.com
Medium sudoku
Nine by nine, where some squares have to be found from the other side.
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Sudoku, Answer Key
9 × 9 · Medium
Created for free at puzzleandprint.com
Or take one that is already made
Four sheets, each a two-page PDF: the puzzles, then the answer key on its own page.
Medium sudoku, one a day9 × 9 · Medium · 1 puzzleDownload PDF ↓
Medium sudoku, pair9 × 9 · Medium · 2 puzzlesDownload PDF ↓
Medium sudoku, four pack9 × 9 · Medium · 4 puzzlesDownload PDF ↓
Medium sudoku, six to a page9 × 9 · Medium · 6 puzzlesDownload PDF ↓Every sheet here is free to print as often as you like. If one saved you time, the tip jar is on Ko-fi.
A medium sudoku here is one that cannot be finished by looking only for squares with a single possible number. Somewhere in every one of these puzzles that runs out, and the way forward is a hidden single: a number that has only one possible square left in a row, a column or a box, even though that square on its own could still take other numbers. Every puzzle on this page needs at least one, and none needs anything beyond it.
How many varies a great deal, which the clue count does not show. Solving the six to a page sheet one easiest step at a time, the grader here placed a single number by hidden single in the fourth puzzle and 24 in the second, although the second starts with more clues: 30 against the fourth puzzle’s 28. The four pack runs from 3 to 13 and the one a day grid took 6.
The four sheets hold the same level in four layouts. One a day gives a single puzzle the whole page, the pair puts two on a page for a sitting with coffee or a homework slot, the four pack fills a page with four, and six to a page is a week of one puzzle a day on one sheet, with squares about a quarter of an inch across.
Medium puzzles start with 28 to 30 clues on these sheets. Every one has exactly one solution and its own grid on the answer key, so a stuck solver can check a single row against the key without seeing the rest of the page solved.
How to spot a hidden single in a medium sudoku
A hidden single is found by starting from a number instead of a square. Choose a number, say 7, and a box that does not have one yet. Every 7 already in the grid rules out the whole row and the whole column it sits in, so draw an imaginary line through each of them across the box. If only one empty square in the box escapes every line, the 7 goes there, even if that square could hold other numbers when looked at on its own.
The same check works along a row or a column instead of a box. On these medium sheets that move is always needed at least once, and the rest of each puzzle falls to the simpler square-by-square scan, so the skill is knowing when to switch: when no square has a single possible number left, start sweeping the numbers one at a time.
Putting the six to a page medium sheet in order
The six to a page sheet holds a week of puzzles with squares about a quarter of an inch across, and its puzzles are not in order of difficulty. Solved the easiest way at each step, puzzle 4 took a single hidden single, puzzles 1 and 5 took three each, puzzle 6 took 13, puzzle 3 took 19 and puzzle 2 took 24.
Working them as 4, 1, 5, 6, 3 and then 2 makes the week climb steadily rather than jump about. For larger squares, the four pack puts four puzzles on a page with squares a little under 0.4 of an inch, and the one a day sheet gives a single grid about 0.8 of an inch to a square.
Common questions
Do the medium sudoku ever need pencil marks?
Not strictly. A hidden single can be found by sweeping one number across a box, row or column and seeing where it can still go, which needs no notes. Some solvers like to mark candidates anyway, and the pair and four pack sheets, with squares about 0.4 of an inch, leave room for it.
Can I print the medium sudoku in letters?
The four ready-made medium sheets use numbers. The maker above prints medium puzzles with A to I instead: choose Letters under Fill with. Letters change only what is written in the squares, so a letters grid is graded exactly as its numbered version would be and still has one solution.
Want to know when new printables go up?
New printables when they go up, mostly seasonal, a few times a year.