SudokuMedium
Medium sudoku
Two larger 9 × 9 sudoku per page at the middle difficulty, each with a single solution. It suits regular solvers who have outgrown beginner grids but want an evening puzzle, not a struggle.
- Fresh problems every time
- Answer key on its own page
- Print or PDF, Letter or A4
- Free, no sign-up
On this page
Medium sits where you must use more than one move, but you rarely have to guess. Two puzzles per page keeps each grid roomy enough to pencil in candidates.
What prints
Each page is titled "Medium Sudoku" and has a one-line rule: each row, column and 3 × 3 box holds the numbers 1 to 9 exactly once. Two grids sit side by side, labeled Puzzle 1 and Puzzle 2. They are drawn as large as the page width allows, with thick box borders and thin cell lines. Starting numbers are bold. The key page repeats both grids with every answer filled in, with the numbers you must find in color.
The settings
- Grid: stays on 9 × 9, while 4 × 4 and 6 × 6 are the shorter boards.
- Difficulty: Medium, between Easy and Hard.
- Puzzles per page: 2, with 1, 4 and 6 also offered.
What medium means here
On a 9 × 9 grid the generator aims for about 31 clues. That is a bit more than 50 empty squares per puzzle. It deletes numbers in random order and, after each deletion, confirms with a solver that exactly one solution remains; if a deletion would allow two, that number goes back. So the count can land slightly above 31, which is why the target is "about" and not exact.
A smaller grid for warm-up is available through the Grid setting, and the 6 × 6 version makes a good test of technique before a full puzzle.
Techniques to try
Look at rows and columns together. If two boxes in a band both already hold a 7, the third box's 7 must sit in the remaining rows, and often only one square fits. Another habit is to count how many of each number are placed; the numbers that appear most are usually the quickest to finish. If you stall, write small candidates in the corners of the three emptiest squares of a box and look for a pair that share the same two numbers.
Worked example: a Sunday crossword-and-sudoku hour
Elaine prints the page as it opens and takes Puzzle 1. She finishes the top-left box, then spots that 4 is already in columns 2 and 3 of the top band, which leaves one place for it. By the time she reaches the bottom, she has used pencil candidates twice. Puzzle 2 she saves for a friend, and they compare against the key, noticing that no solution needed a guess.
Where next
Once this feels routine, move to hard sudoku. For a break from numbers, the printable crossword puzzles page has word grids with clues.
Sources
- NRICH, University of Cambridge: Logic problems and puzzles nrich.maths.org