gistfile1.txt

 def total_qty
                  
          self.ys_qty.to_i + self.ym_qty.to_i + self.yl_qty.to_i
           + self.yxl_qty.to_i + self.s_qty.to_i + self.m_qty.to_i
           + self.l_qty.to_i + self.xl_qty.to_i +  self.two_xl_qty.to_i
           + self.three_xl_qty.to_i + self.four_xl_qty.to_i
           + self.five_xl_qty.to_i + self.six_xl_qty.to_i
  end

rails c

@job
 => #<Job id: 2, created_at: "2012-11-12 18:46:16", updated_at: "2012-11-12 18:52:29", total_qty: nil, shirt_quality: "Standard", art: nil, customer_id: 1, turn_around: "Rush! (shipped in 1-3 days)", art_file_name: nil, art_content_type: nil, art_file_size: nil, art_updated_at: nil, ys_qty: 101, ym_qty: 10, yl_qty: 10, yxl_qty: 10, s_qty: 100, m_qty: 10, l_qty: nil, xl_qty: nil, two_xl_qty: nil, three_xl_qty: nil, four_xl_qty: nil, five_xl_qty: nil, six_xl_qty: 10, placement: "Placement", special_instructions: ""> 
1.9.3-p0 :006 > @job.total_qty
 => 10