For rectangular surfaces:
\[ S = \frac{(L \times W \times D)}{27} \]
For circular surfaces:
\[ S = \frac{(\pi \times \left(\frac{L}{2}\right) \times \left(\frac{W}{2}\right) \times D)}{27} \]
Considering waste factor:
\[ S_T = S + \frac{S}{10} \]
