Packed number is too small?

Howdy,

I have the following code that gives me an ABAP dump when the calculation prodcues a figure like 136.9778007

data: dc    TYPE p DECIMALS 13,

FORM calculate_dc USING  lv_matcostprice                    
lv_factor                  lv_rate                              
CHANGING lv_dc.                                                                                
lv_dc = lv_matcostprice / lv_factor * 
           100 / lv_rate.          
 ENDFORM.                    "cALCULATE_DC                 

Can anyone see why it would be doing this?