静心约分

Equal: Two tiles with the same number → both disappear.
5 + 5 → ∅

Divide: Smaller divides larger evenly → smaller disappears, larger becomes larger/smaller.
13 + 65 → 5 (13 gone)
6 + 24 → 4 (6 gone)
3 + 9 → 3 (3 gone, 9 becomes 3)

约分 (Reduce): Two numbers sharing a factor (>1) → both get divided by their GCD.
12 + 8 → 3, 2 (gcd=4, so 12/4=3 and 8/4=2)
18 + 24 → 3, 4 (gcd=6)

Connectable: Adjacent, OR a line path through empty cells with at most 2 turns. Path can go around the edge.

Watch for: Perfect squares (4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289) and cubes (8, 27, 64, 125, 216) — they create rich divide and GCD chains.