No, diagonal numbers do not count as adjacent in Number Match 10. Only pairs that share a horizontal or vertical edge qualify as a legal match, and only those pairs are eligible to be removed from the board. This single rule is the foundation of the entire puzzle: every other mechanic, from scoring to deadlock detection, follows directly from how adjacency is defined. Diagonal neighbors, by contrast, are treated as completely separate cells. They may look close on the screen and even add up to 10, but the board will not let you select them together, and the removed-pair logic will reject them as well. The rule exists because the puzzle is built around a Manhattan-distance check: a legal pair must have a Manhattan distance of exactly one cell, which means sharing a side, not a corner. Understanding this distinction early prevents the most common mistake new players make, which is treating the puzzle as a simple make-ten exercise and wondering why their pair never disappears. If you want to see this rule in action, you can play it directly in the Number Match 10 tool and watch how diagonal selections are rejected at every step.
What "Adjacent" Means in Number Match 10
Adjacency in this puzzle is strictly orthogonal, which is a precise way to say "side-sharing." Two cells are adjacent in Number Match 10 only when they sit directly next to each other in the same row or in the same column. A 1 sitting to the immediate left or right of a 9 is adjacent. A 2 sitting directly above or below an 8 is adjacent. A 3 that touches a 7 only at the corner is not adjacent, regardless of how close the two cells look visually or whether they happen to add up to 10.
This matches the broader convention used by many logic-puzzle genres, from Slitherlink to Nurikabe to Tents, where diagonal touching is treated as a separate relationship rather than as adjacency. In Number Match 10 the convention is enforced both at the input layer (your keyboard choices) and at the pure logic layer that maintains the board state. If you try to select a cell that is only diagonal to your first selection, nothing disappears, your newer cell simply becomes the active selection, and you can move to a real neighbor on the next attempt. The system never tells you the pair was "diagonal" in plain text; it just refuses to remove the numbers and lets you keep playing.
How to Play Number Match 10
The game has a tiny surface but a strict sequence, and following these steps in order is the cleanest way to learn the orthogonal adjacency rule through actual play.
- Move the visible cursor over the 2x3 board with the arrow keys until it sits on the first number you want to match.
- Press Space or Enter to select that number. The first square is now highlighted as the active selection.
- Move the cursor one step to a horizontally or vertically neighboring cell. The cursor must share an edge with the first selection, not just a corner.
- Press Space or Enter again to lock in the second number. The board checks two conditions: that the two cells are orthogonally adjacent and that their values sum to exactly 10.
- If both conditions hold, the pair disappears and your score increases by 100 points. The cursor remains where it last sat so you can continue selecting the next pair.
- If either condition fails, no numbers disappear. The newer square becomes the first selection for your next attempt, and the board stays exactly as it was.
- Continue clearing legal pairs until all six cells are removed, at which point you finish with a score of 300. If the remaining numbers can no longer reach 10 across an edge, the board reports a deadlock and prompts you to restart.
The 2x3 Board and Its Initial Legal Pairs
The fixed layout of Number Match 10 has two rows and three columns. The top row reads 1, 9, 1 from left to right. The bottom row reads 9, 2, 8 from left to right. With those six values in place, there are exactly four orthogonal edges that connect cells whose values sum to 10, and those four edges are the only legal matches available at the start of a fresh game.
| From cell | To cell | Values | Sum | Edge type |
|---|---|---|---|---|
| Top-left (0) | Top-middle (1) | 1 and 9 | 10 | Horizontal |
| Top-middle (1) | Top-right (2) | 9 and 1 | 10 | Horizontal |
| Top-left (0) | Bottom-left (3) | 1 and 9 | 10 | Vertical |
| Bottom-middle (4) | Bottom-right (5) | 2 and 8 | 10 | Horizontal |
The top-left 1 has two neighbors that work (top-middle 9 and bottom-left 9). The top-right 1 only has one (top-middle 9). The bottom-left 9 only connects up to the top-left 1. The bottom-middle 2 only reaches the bottom-right 8. Because removed cells stay empty rather than collapsing, every remaining adjacency stays visible for the rest of the game, which makes the order of removal matter more than it does in most matching puzzles.
Why a Diagonal-Only Match Creates a Deadlock
The fixed 300-point route on this board is to clear the vertical left column first (1 on top, 9 below), then clear the horizontal top row pair (9 and 1 in cells 1 and 2), then clear the bottom 2 and 8 in cells 4 and 5. Every removed pair in that sequence leaves the remaining numbers connected by an actual shared edge. The board does have an alternate tempting route, however, and it is the clearest way to see why diagonal adjacency matters.
If you first remove the top-left 1 with the top-middle 9, then remove the bottom-middle 2 with the bottom-right 8, you have removed cells 0, 1, 4, and 5. The numbers still on the board are the top-right 1 in cell 2 and the bottom-left 9 in cell 3. Those two numbers do add up to 10, but cell 2 is at the top-right corner of the board and cell 3 is directly below cell 0, which is now empty. Cells 2 and 3 share only a corner, not an edge, so they are diagonal, not adjacent. The board sees that there are still two numbers left but zero legal pairs and immediately asks you to restart. You can read more about how this same trap shows up in the dedicated guide on legal-match deadlocks in Number Match 10.
Legal vs. Illegal Pair Types at a Glance
For quick reference, every pair in Number Match 10 falls into one of three categories. The board treats all three differently when you press Space or Enter on your second selection.
| Pair type | Example | Result |
|---|---|---|
| Horizontal or vertical edge, sum equals 10 | Top-left 1 with top-middle 9 | Both cells disappear, +100 points |
| Horizontal or vertical edge, sum is not 10 | Top-middle 9 with bottom-middle 2 | Nothing disappears, second cell becomes new selection |
| Diagonal corner, sum equals 10 | Top-right 1 with bottom-left 9 | Nothing disappears, second cell becomes new selection |
Only the first row is ever a winning move. The second and third rows are the two ways the board silently rejects a selection, and they look identical to the player because in both cases nothing changes on screen. The only way to know which rule fired is to count the cells and read the values yourself.
How the Browser Detects That No More Moves Exist
Behind the keyboard interface, the game keeps a Set of removed indices over the fixed value list [1, 9, 1, 9, 2, 8]. On every selection it enumerates the pairs of cells that have not yet been removed, checks that their Manhattan distance is exactly one, and confirms that the two values add up to 10. If at any moment cells remain but the enumeration produces an empty list, the board declares a deadlock and offers a Restart that restores all six numbers, clears the selection, returns the cursor to cell 0, and resets the score to 0. The check happens immediately, so a deadlock never lingers silently for a turn. That instant feedback is also why the orthogonal adjacency rule feels so firm: there is no fuzzy case where a pair "almost" works, only an exact Manhattan distance of one paired with an exact sum of 10.
Other Rules That Affect Your Choices
A few smaller rules round out the game and reinforce the diagonal-not-adjacent principle. Pressing Space or Enter on the same square twice cancels the selection entirely, so you can back out of a mistaken first choice without committing to anything. Removed cells cannot be re-selected, even if a value would technically sum to 10 with one of them. The board never collapses and never applies gravity, so the original two-by-three positions stay fixed for the entire game. Selecting a number that does not add to 10 with its chosen neighbor is treated as a fresh first selection rather than as an error, which means the puzzle gives you unlimited attempts to find a legal pair. Combined, those rules guarantee that every legal move is exactly the orthogonal make-ten pair the title promises and nothing else.