gistfile1.txt

class Numeric
  def negative
    if self <= 0
      self
    else
      self * -1
    end
  end
end

-123.negative                         # => -123
123.negative                          # => -123
0.negative                            # => 0
123.5.negative                        # => -123.5
BigDecimal('123.45').negative.to_s    # => "-123.45"

class Numeric
  def negative_abs
    self.abs * -1
  end
end

-123.negative_abs                         # => -123
123.negative_abs                          # => -123
0.negative_abs                            # => 0
123.5.negative_abs                        # => -123.5
BigDecimal('123.45').negative_abs.to_s    # => "-0.12345E3"

Yup... just went with that one! Great minds... odd I never solved this before :)
Took me forever to come up with .