Sudoku looks like a math puzzle, but it uses no arithmetic at all. It is pure logic, and once you learn a few scanning habits the easy and medium grids fall quickly.
A sudoku grid is nine rows, nine columns, and nine boxes of nine cells. Fill every empty cell so that each row, each column, and each 3x3 box contains the digits 1 through 9 with no repeats. That single rule drives every technique below.
Pick a digit, say 5, and look across the grid. Wherever a row, column, or box already has a 5, that digit cannot repeat there. Often you find a box where only one empty cell could possibly hold the 5. Place it. Working one digit at a time this way clears most easy puzzles without any advanced tricks.
When scanning stalls, lightly note the candidate digits that could fit each empty cell. A cell with only one candidate is a certainty, so fill it. When a candidate appears only once in a row, column, or box, it belongs there even if the cell lists others. Pencil marks turn a stuck grid into a series of small certainties.
A proper sudoku has exactly one solution reachable by logic, so guessing is unnecessary and usually leads to a dead end you cannot undo cleanly. If you are stuck, you have missed a scan, not run out of logic. Re-check each digit across the whole grid before you assume you are blocked.
Speed comes from pattern recognition, not rushing. The more grids you solve, the faster your eye spots the forced cell. Start with easy puzzles until singles feel automatic, then step up. Print a fresh grid whenever you want a calm, finishable challenge.
Generate a printable sudoku at the size and difficulty you want with the free sudoku maker, and print the answer key to check your logic. For a change of pace, try the maze maker or a word search.