NS-010

Find the next number: 13, 15, 19, 25, 33, ?

Rule: The gaps increase by 2 each time: +2, +4, +6, +8, then +10.

So the next number is 43.

• Picking the first pattern you see without checking it against all rows/columns.
• Ignoring the simplest rule (counts, rotations, alternations) and jumping to a complex story.
• Not testing your rule on the middle row/column (where many puzzles “break” bad rules).