GridWits
Extreme tier Technique 37 of 46 Reference only

Bowman's Bingo

Last Resort: guess a candidate and manually trace forced Naked/Hidden Singles as far as they go — a contradiction eliminates the guess, same idea as Trial and Error but tracked by hand.

The solver does not attempt this technique, so Smart Hint will never suggest it. It is documented because you may still want to spot it yourself.

How it works

  1. 1Guess A1 = 1, then call out only the Singles that guess forces — no other technique, and no second guess partway through.
  2. 2E1 shares row 1, so it drops to 4. A5 shares column A, so it drops to 7.
  3. 3Now look at E5: it sees E1 down column E and A5 across row 5, so both of its candidates are gone and the cell has nothing left to hold.
  4. 4The guess broke the board, so A1 is 9. The name is for calling each forced placement out in turn, bingo-style — it is the ancestor of the modern Forcing Chains.

Play a Sudoku that needs this technique →

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 1 9 1 4 1 7 4 7 1
  • First colour in the chain
  • Second colour in the chain
  • Where the conclusion lands
  • Candidate ruled out
Next in the ladder Unique Rectangle →

Uses the fact that a proper Sudoku has exactly one solution to rule out candidate patterns that would create a second, deadly duplicate.