In this example, we are going to calculatethe quantity of bricks needed to cover an outside wall with the Active Takeoff Length tool. The bricks can be replaced by any other estimating item that contains an area coverage rate (panels, rolls, tiles etc.)
 
On the plan, we have measured a wall length of 60'-10" with the Length tool. 
Insert the brick item in the usual way:
 
Once the "Select" button is clicked, the Formula builder will open.


Here is the composition of the formula to get an area. This area will be divided by the covering rate of the brick in order to obtain the actual quantity of bricks to cover the area: 60'-10" (supplied by the [Length] variable) multiplied by a constant height of 8'-4" (entered by the user): 
Result: 3474 bricks

Variation 1: Rounding the quantity to the upper unit with the "ceiling" function $ceil(). The expression to be rounded must be enclosed in the parentheses : 
$ceil([Length] * 8'4")

Variation 2: Adding a waste factor in the form of a constant. A 5% waste factor will be represented by the 1.05 constant, a 20% waste factor will be represented by the 1.20 constant.

Result : 
 
Add as many items as needed (Other materials, labor, equipments, sub-contractors) by repeating this process in order to get all the required estimating items for your quote. These assemblies can also be saved as a template so you can save time in your next takeoff.