Method: Integer#factorial

Defined in:
lib/core/facets/integer/factorial.rb

#factorial ⇒ Object Also known as: fac

Calculate the factorial of an integer.

 2.factorial  #=> 2
 3.factorial  #=> 6
 3.factorial  #=> 24

CREDIT: Malte Milatz



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# File 'lib/core/facets/integer/factorial.rb', line 11

def factorial
  return 1 if zero?
  f = 1
  2.upto(self) { |n| f *= n }
  f
end