# File lib/rational.rb, line 173
  def * (a)
    if a.kind_of?(Rational)
      num = @numerator * a.numerator
      den = @denominator * a.denominator
      Rational(num, den)
    elsif a.kind_of?(Integer)
      self * Rational.new!(a, 1)
    elsif a.kind_of?(Float)
      Float(self) * a
    else
      x, y = a.coerce(self)
      x * y
    end
  end