Printable Hard Sudoku — April 21, 2026 | Internet Sudoku

Internet Sudoku

Sudoku Tips

Sudoku gets easier when you solve with a repeatable scan instead of searching the whole grid at once.

Tip 1: Look for rows, columns, or 3 by 3 boxes that already contain several numbers. The more filled-in an area is, the fewer places a missing digit can go.
Tip 2: Work one number at a time. Scan every box for where that number can still fit, then compare those open spots with the crossing rows and columns.
Tip 3: Use notes when a square has only a few real candidates. After every confirmed number, clean up notes in the same row, column, and box.