All Sudoku Variants
9×9 · Constraint

Numbered Rooms Sudoku

An outside clue names the digit sitting in the Nth cell of its row or column, where N is the digit in the cell nearest the clue.

5 7 1 4 8 4 1 9 1 4718

An example Numbered Rooms puzzle. Beside row 1 the clue 7 reads: the nearest cell is 5, so the 5th cell along holds 7.

Numbered Rooms Sudoku writes a small clue digit outside some rows and columns. The clue is not a sum — it names the digit that sits at a specific position, and that position is chosen by the puzzle itself: read the cell nearest the clue, and its value tells you how far to count in. It is a close relative of X-Sums, where the nearest cell decides a reach the same way.

The rule: the first cell points to the answer

Let N be the digit in the cell nearest a clue. Then the clue is the digit in the Nth cell, counting inward from that edge. Below, the clue "7" sits beside a row whose first cell is 4 — so the 4th cell must be a 7.

7 4 2 9 7

The nearest cell is 4, so count to the 4th cell — it holds the clue digit 7.

A worked example, step by step

Step 1 — read the pointer. The cell touching the clue is the "pointer": its digit N is how many cells to count. Nothing else can be read until that cell is known, so pointer cells are the first thing to resolve.

Step 2 — count inward. Step N cells in from the edge and drop the clue digit there. If the pointer is 1, the clue digit lands in the first cell itself — the clue is self-describing.

Step 3 — work it backwards too. The relationship runs both ways: if you already know where the clue digit is, its position tells you what the pointer cell must be. A "7" found in the 4th cell forces the first cell to be 4.

Solving strategy

  • Chase the pointer. Once the nearest cell is fixed, the clue instantly places a second digit deeper in the line.
  • Read it in reverse. Knowing where the clue digit sits pins the pointer cell — often the easier direction.
  • Mind the small pointers. A pointer of 1 or 2 keeps the clue digit right by the edge, tightly constraining the near box.
  • Feed the grid. Every digit a clue fixes behaves like a given for its row, column and box.

Common mistakes

  • Treating the clue as a sum. It is a positional pointer, not a total — the nearest cell chooses where, not how much.
  • Counting from the wrong end. Always count inward from the edge the clue is written on.
  • Forgetting the self-reference. A pointer of 1 puts the clue digit in the pointer cell itself.
  • Dropping ordinary Sudoku. The placed digits must still obey their row, column and box.

Can I play it here?

Not yet — Numbered Rooms Sudoku isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile: