text: Step 1:  We take layer 1 as x, and layer 2 as y.  By our assumptions in this case,  {  }.                
  Step 2:  We take the result from step 1 as the value for new x [ x is old x+y; (-x) is old y+x ], and the value for layer 3 as new y.
  <math>T_{x+y} = \frac {T_x T_y}{1-R_{(-x)} R_y} = \frac {(0.912)(0.96)}{1-(0.0361)(0.04)} =0.877 = T_{123}
  Dahm has shown that for this special case, the total amount of light absorbed by the interior of the sheet (considering surface remission) is the same as that absorbed in a single trip (independent of surface remission).    This is borne out by the calculations.
  The decadic absorbance () of the sheet is given by: