It is possible to calculate SUM and COUNT totals for the accumulation of a specific Element in a Loop. For more information on Loop Elements, please see this article: Configuring Loops
Elements that come after a Loop Element can make use of these roll-up calculations in their formulas by using the following syntax: SUM(ElementName) and COUNT(ElementName), where ElementName refers to an element encapsulated by a Loop Element that needs to be summed or counted - Don't forget the square brackets  !
It should also be noted that these formulas only work with specific Element Types:
- SUM works only with Numeric Elements
- COUNT works with Text, Numeric, Picklist and Date Elements
Example Roll-Up Formulas
Here is a Loop about windows. This example Form includes:
- Two Elements within the Loop that contain the window height and location: 'WindowHeight' and 'WindowLocation'.
- Two Elements outside of the Loop for calculating the total number of windows and total height of all of the windows: 'TotalWindowCount' and 'TotalWindowHeight'.
1. To find the total SUM of the height of the windows, you can use a formula for the Default Value of the TotalWindowHeight element and reference the 'WindowHeight' element field encapsulated by the Loop Element. Use the Formula: 'SUM(WindowHeight)' to add up all the values entered in the WindowHeight element field for all loop iterations and populate a total.
2. You can find the total COUNT of the amount of windows data has been recorded for by referencing any of the elements within the Loop. Use the formula: 'COUNT(WindowLocation)' to count the number of times 'WindowLocation' has been displayed in the Loop and populate how many windows there are in total. .