The formula to calculate the number of posts is:

$$\text{Number of Posts} = \frac{\text{Fence Length (ft)}}{8} + 1$$

The formula to calculate the total number of rails is:

$$\text{Total Number of Rails} = (\text{Number of Posts} - 1) \times \text{Number of Rails}$$

The formula to calculate the number of pickets is:

$$\text{Number of Pickets} = \frac{\text{Fence Length (ft)} \times 12}{\text{Picket Width (in)} + \text{Picket Gap (in)}}$$

The formula to calculate the amount of cement bags is:

$$\text{Cement Bags} = \begin{cases} 3 & \text{if } \text{Fence Length} < 9 \\ 4 & \text{if } 9 \leq \text{Fence Length} < 19 \\ 5 & \text{if } 19 \leq \text{Fence Length} < 29 \\ \lceil \frac{\text{Fence Length}}{10} \rceil + 2 & \text{if } \text{Fence Length} \geq 29 \end{cases}$$

The formula to calculate the amount of 1-1/2" screws/nails is:

$$\text{1-1/2" Screws/Nails (lbs)} = \lceil \frac{\text{Fence Length}}{20} \rceil$$

The formula to calculate the amount of 3-1/2" screws/nails is:

$$\text{3-1/2" Screws/Nails (lbs)} = \lceil \frac{\text{Fence Length}}{30} \rceil$$