SudokuloftA handful of numbers. Everything in balance.
Targets appear beside rows and below columns. Any valid arrangement counts.
Opening your notebook…
Your answers save in this browser. Take a break whenever you like.
Use each number exactly once so every row and column equals its printed target. The filled squares with a small dot are fixed clues. Any arrangement satisfying all the totals is a valid solution; you do not have to guess a hidden order.
Targets to the right belong to rows; targets below belong to columns. The smaller number shows your running sum. This 3 × 3 example uses every number from 1 to 9 once. Printed 5, 9 and 2 are starting clues and cannot be moved.
The middle row already contains 5 and 9, which total 14. Its target is 18, so the missing number is 4. Select the empty square and choose 4 from the tray. That number is now used and cannot go in another square.
Each number belongs to both a row and a column. In the solved example, 6 is part of row 1 + 6 + 3 = 10 and column 6 + 5 + 7 = 18. A full group shows a check when correct, or an × when its total needs adjustment.
Fill every editable square and meet all row and column targets. Repeating 5 in the left example breaks the once-only rule. Easy and Medium use 1–9 on 3 × 3, with fewer fixed clues in Medium. Hard uses 1–16 on 4 × 4.
Every square must be filled, every number used once and every row/column target met. A row check alone is not enough: its numbers must also work with the columns.
A number that completes one row may make another column impossible. Erase or Undo a recent guess if Hint cannot find a continuation. A fixed clue, marked with a dot, cannot be changed.
Select a square and tap a tray number, or type 1–9. Use the tray for 10–16. Arrow keys move between squares. Backspace or Erase clears an editable square; Undo reverses a placement. Hint searches for a valid continuation of your current answers, and places one number when it finds one.
Every puzzle is open from the start. Switching puzzles keeps your accepted answers, and Restart clears only the current attempt after confirmation. Your solved record remains. Progress stays in this browser; clearing site data removes it, and another device or browser has its own notebook.