page_title: Slitherlink
section_title: A rule for squares with 2
hierarchical_section_title: Slitherlink / Solution methods / Exactly 2 or 0 lines at each point / A rule for squares with 2
caption_attribution_description: English: A partial Slitherlink game showing the knowledge gained when a line is adjacent to a 2 with a blank area.
context_page_description: Slitherlink is a logic puzzle developed by publisher Nikoli.
context_section_description: If a 2 has any surrounding line X’d, then a line coming into either of the two corners not adjacent to the X’d out line cannot immediately exit at right angles away from the 2, as then two lines around the 2 would be impossible, and can therefore be X’d.  This means that the incoming line must continue on one side of the 2 or the other. This in turn means that the second line of the 2 must be on the only remaining free side, adjacent to the originally X’d line, so that can be filled in.
   
  Conversely, if a 2 has a line on one side, and an adjacent X’d out line, then the second line must be in one of the two remaining sides, and exit from the opposite corner (in either direction). If either of those two exits is X’d out, then it must take the other route.
caption: A 2 next to a line.
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