10 Sudoku Tips That’ll Help You Win

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What is the swordfish technique in Sudoku?

You won’t need a Sudoku strategy involving the swordfish technique when just learning how to play Sudoku—not every puzzle has a swordfish pattern—but as you progress, you may run into this technically challenging puzzle pattern—and it may confound you.  “A Swordfish pattern occurs when three rows (or three columns) each contain two or three cells that hold a matching locked candidate,” according to Sudoku Essentials. This candidate must reside in each of the three rows and share the same three columns or vice versa.” Once you master this Sudoku strategy, try to solve the hardest puzzle ever.

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What is a jellyfish in Sudoku?

A jellyfish is when, “Four columns have a candidate in only four different rows, or vice versa,” per Sudoku Snake. The self-described, most advanced Sudoku application goes on to say that a jellyfish is like an, “X-Wing or Swordfish expanded into four units. The columns or rows that have these candidates are the primary units, and must only contain the candidates in the other four rows or columns called the secondary units. All other candidates in the secondary units can be eliminated.” A jellyfish may leave you scratching your head more than these 15 complex word puzzles!

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What is a unique rectangle in Sudoku?

Somewhat of a controversial subject in the Sudoku world, a unique rectangle (UR) is a situation in which a puzzle may have two different solutions. Hodoku notes that, “A unique rectangle consists of four cells that occupy exactly two rows, two columns, and two boxes. All four cells have the same two candidates left (in real Sudoku, not all cells have to hold all of the UR candidates).” Ready for more? Try these 17 hard math problems that will make your head spin.