Killer Sudoku by Sudoku.com

Fill the 9x9 grid so each row, column, and 3x3 box contains numbers 1-9 without repeats. Read the dotted cages and make sure the digits inside each cage add up to the shown total with no repeats. Start with extreme cages and guaranteed singles to place obvious numbers early. Use Notes to pencil in candidates and let automatic updates narrow possibilities as you progress. Apply killer strategies like cage combinations, intersection removal, and arithmetic elimination to advance without guessing. Challenge yourself with daily puzzles and higher difficulties, using Hint, Undo, and Erase to refine your approach and improve times.