Rule of three

Rule of three may refer to:

Science and technology

• Rule of three (C++ programming), a rule of thumb about class method definitions
• Rule of three (computer programming), a rule of thumb about code refactoring
• Rule of three (mathematics), a method in arithmetic
• Rule of three (medicinal chemistry), a rule of thumb for lead-like compounds
• Rule of three (statistics), for calculating a confidence limit when no events have been observed
• Rule of three (hematology), a rule of thumb to check if blood count results are correct

Other

• Rule of three (aviation), a rule of descent in aviation
• Rule of three (economics), a rule of thumb about major competitors in a free market
• Rule of threes (survival), a quick reference for how long one can survive in an emergency situation
• Rule of Three (Wicca), a tenet of Wicca
• Rule of three (writing), a principle of writing
• Rule of Three, a podcast by Jason Hazeley and Joel Morris
• Rule of Three, a series of one-act plays by Agatha Christie
• The Bellman's Rule of Three in The Hunting of the Snark, a poem by Lewis Carroll

See also

• Three-sigma rule, for a normal distribution in statistics
• Triumvirate, a political regime dominated by three powerful individuals
• Rule of thirds, a compositional rule of thumb in photography
• Rule of thirds (diving), a rule of thumb for scuba divers
• Rule of thirds (military), a rule of thumb regarding the distribution of available manpower