Sudoku looks like a math puzzle, but there’s no arithmetic at all: it’s pure logic. If you can spot which number is missing from a row, you can solve an easy Sudoku. Here’s how to start.
The rules
The grid is 9×9, split into nine 3×3 boxes.
Fill every empty square with a number from 1 to 9.
Each row, each column and each box must contain every number exactly once.
Every puzzle has exactly one solution, and you never need to guess.
Technique 1: the only number that fits
Pick an empty square and look along its row, its column and its box. Cross off every number you see. If only one number is left, that’s the answer. Easy puzzles can be solved with this almost entirely.
Technique 2: the only place a number can go
Pick a number, say 5, and a box that doesn’t have one yet. Look at the 5s in nearby rows and columns: each one rules out a line through the box. If only one square in the box is left, the 5 goes there. Doing this for each number in turn fills a lot of squares quickly.
Tools that help while you learn
Start on Easy: more numbers are given, and these two techniques are enough.
Notes let you pencil in candidates for a square, so you can keep track.
Mistakes are counted when a number is wrong, so you learn as you go.
Hint fills in a square when you’re stuck. Undo takes back any move.
What to try next
When Easy feels quick, move up to Normal, or try the daily Sudoku: one puzzle a day, the same for everyone. For a smaller start there’s Mini Sudoku (6×6), and for a twist there’s Killer Sudoku and Jigsaw Sudoku.