Number Link — Connect Matching Number Pairs
Draw paths to connect matching number pairs without crossing. Click cells to build a path.
How to play
- Click a numbered circle to start drawing that pair's path.
- Click cells adjacent to the path tip to extend it one step at a time.
- Reach the matching number to complete that pair's connection.
- Fill every cell to solve; use 'Clear Paths' or 'New Puzzle' to restart.
Connect each pair of matching numbers with a path. Click a numbered cell to start, then click adjacent cells one step at a time to extend the path until it reaches its twin. Paths can't reuse cells, so plan carefully — fill every cell to fully solve it.
How it works
Number Link (also known as Flow or Numberlink) presents a grid with pairs of numbered cells. Your task is to draw a continuous path connecting each matching pair. The paths must not cross each other, and every cell on the grid must be part of exactly one path when the puzzle is complete.
The fill-the-board constraint is what makes the puzzle nontrivial: it is not enough to simply connect each pair by any route. Paths must collectively occupy every cell, which means you must route each one carefully to avoid leaving isolated, unreachable cells.
A reliable solving approach is to start with pairs that are close together or separated by a narrow corridor where few routing options exist. Once a constrained path is fixed, it walls off sections of the board for the remaining paths. Corner cells are especially useful: a corner cell belonging to a specific number can only be reached from two directions, sharply limiting routing choices.
Number Link trains logical deduction, spatial planning, and constraint satisfaction — skills that transfer directly to circuit board routing and network planning in engineering.
Worked example
Solve a 5x5 Number Link grid
- Identify the pair closest to a corner — say, pair 1 with one cell in the top-left corner.
- A corner cell has only two possible exit directions; one is likely blocked by the grid edge, leaving one valid start.
- Trace the only feasible path for pair 1 given the corner constraint.
- Now look at which cells the path walled off and use that to constrain the next most restricted pair.
- Continue resolving paths from most-constrained to least-constrained until every cell is filled.
All pairs connected, every cell covered, no paths crossing.
Common mistakes to avoid
- Connecting a pair by the shortest route without thinking about whether that leaves unreachable empty cells elsewhere on the board.
- Routing a long pair first and boxing in shorter pairs so they cannot reach each other.
- Finishing all connections but leaving empty cells — that means the solution is incomplete even though all numbers are paired.
Key terms
- Path
- A connected sequence of cells from one numbered endpoint to its matching partner, passing through intermediate cells.
- Crossing constraint
- The rule that no two paths may share a cell — paths can only meet at their own endpoints.
- Constraint propagation
- Using already-fixed paths to eliminate impossible routes for remaining unresolved pairs.
Frequently asked questions
- How do I draw a path?
- Click a numbered cell to begin, then click cells one at a time — each must be adjacent (up/down/left/right) to the path tip — until you reach the matching number.
- Can paths cross?
- No. Each cell can belong to only one path, so paths can never overlap or cross.