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Puzzles · Nonogram

Nonogram: see which cells are certain

A nonogram hides a picture behind numbers. Every cell can be worked out from the clues, so you never need to guess. This page teaches five ways to find a certain cell, and its hints show the reasoning. They never colour a cell for you.

The rules in one minute

  1. The numbers beside each row and above each column list its blocks of filled cells, in order. “3 1” means a block of three, then a block of one.
  2. Blocks in the same line are separated by at least one empty cell. A line marked 0 is empty.
  3. Fill every cell the clues require and the picture appears. Each picture here has exactly one solution.

Use Cross to mark cells you know are empty. Those marks are your own notes, and several techniques build on them.

Practise

Pick a size. Every picture is an origami model or a Rubik's Cube from this site, and when you finish one you can open its guide.

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Keyboard: arrow keys move, Space marks with the current tool, X crosses out, T switches tool, Backspace clears.

How hints work

Each press of Hint reveals a little more of the same reasoning: first which line to look at, then the technique's name, then the evidence, and finally a guided walk-through on your own board. You always mark the cells yourself.

Five techniques, one beat at a time

Each lesson works on one line in five beats: where to look, the evidence, your turn to decide, the conclusion and the rule to remember. In the evidence, the blocks are packed to the left (upper bars) and to the right (lower bars).

  1. 1

    Full line

    When the blocks and the gaps between them fill the free space exactly, the whole line is decided.

    2112
    1. Look
    2. Evidence
    3. Your turn
    4. Conclusion
    5. Remember

    Look at this line. Its clue is 2 1 1 2.

  2. 2

    Overlap

    Pack the blocks to the left, then to the right. Cells a block covers both times are filled in every arrangement.

    9
    1. Look
    2. Evidence
    3. Your turn
    4. Conclusion
    5. Remember

    Look at this line. Its clue is 9.

  3. 3

    Unreachable

    A cell that no block can reach, or a gap too short for any block, is empty.

    3
    1. Look
    2. Evidence
    3. Your turn
    4. Conclusion
    5. Remember

    Look at this line. Its clue is 3, and some cells are already crossed out.

  4. 4

    Punctuating

    A run of filled cells as long as every block that could cover it is complete: close it with an empty cell at each end.

    1
    1. Look
    2. Evidence
    3. Your turn
    4. Conclusion
    5. Remember

    Look at this line. Its clue is 1.

  5. 5

    Edge

    A filled cell must be covered by a block. That pins the block close to it: fill towards the cell and cross out what the block can no longer reach.

    2
    1. Look
    2. Evidence
    3. Your turn
    4. Conclusion
    5. Remember

    Look at this line. Its clue is 2, and some cells are already filled.