No given numbers — just dashed cages with sums. You must use 129 logic plus arithmetic. Excellent for elimination skills.
The number 9 appears everywhere in Sudoku: 9 rows, 9 columns, 9 boxes, digits 1–9. The 129 better player treats each 9-cell unit as a complete set needing all digits. sudoku 129 better
When logic fails to reveal a direct elimination, advanced solvers use "Chaining" or "Coloring." Sudoku 129 Better: Master the Grid with Precision,
This involves picking a candidate that only appears twice in a row and following the chain of logic. If Cell A is a 5, then Cell B cannot be a 5
Eventually, this chain will lead to a contradiction (two 5s in the same box, or a cell with zero candidates). When you hit a contradiction, you know your starting assumption was wrong—the chain is impossible, and you can eliminate that candidate. This is pure logic at its finest.