Number sense
Recognize useful combinations and estimate how far the current sum is from the target.
Visual search and number sense
Sum Link
Connect neighboring numbers until their total matches the target. Find as many paths as you can in 90 seconds.
Current sum0 / 15
About Sum Link
Visual search meets mental arithmetic
Sum Link is a 4×4 number-path game. Choose any starting circle, then connect horizontal, vertical, or diagonal neighbors until their values add up to the target. A correct path scores one point and refreshes only the numbers used, creating a new search problem without replacing the entire board.
The 90-second boundary keeps each round short. While the arithmetic uses small numbers, finding a useful route requires you to scan alternatives, remember a running total, and plan around cells that cannot be reused within the same path.
Path planning
Choose an adjacent route that reaches the total without trapping the next move.
Visual scanning
Search the full grid for promising starts while ignoring combinations that cannot connect.
Practice well
Find combinations before tracing
Scan for two-number combinations near the target, then look around them for a small value that closes the gap. For longer routes, keep the remaining amount in mind rather than repeatedly recounting the whole path. Diagonal moves are allowed, but every selected circle must directly touch the previous one.
Use Easy to build familiarity with common sums, Normal for balanced play, and Hard when you want longer combinations. Going over the target does not cancel a path automatically, but releasing an incorrect total scores nothing. Favor clean, intentional routes over frantic swipes.
Common questions
About this exercise
Can I connect numbers diagonally?
Yes. All eight neighboring directions are valid: horizontal, vertical, and diagonal. Non-neighboring circles cannot be added to a path.
Can the same circle be used twice?
Not within one path. After you release, every circle becomes available again; circles in a successful path receive new values.
Does the target change after I score?
No. The target stays fixed for the full 90-second round, while only the successfully used numbers refresh.