Insert Calculated Result
Pastes the result of a calculation into the current field in the current record.
Insert Calculated Result [Select; <table::field>; <formula>]
Select entire contents replaces the contents of a field. If you don't select this option, Insert Calculated Result replaces only the selected portion of the current field, or inserts the result at the insertion point. The default insertion point is at the end of the field's data.
Select Go to target field or click Specify to specify the field to paste the calculated results into. The target field must be present on the layout to paste successfully. If no field is active when the script is performed, the step has no effect.
Calculated result: Click Specify to define the calculation whose results will be inserted by this script step. In the Specify Calculation dialog box, type the calculation you want evaluated, or use the field list (on the left) and the functions list (on the right) with the mathematical and text operators to build the calculation.
Note  If the specified field does not exist on the layout where the script is being performed, Insert Calculated Result returns an error code which can be captured with the Get(LastError) function.
This script step is also supported in web publishing and in a FileMaker Server scheduled script.
Originated in 
FileMaker Pro 6.0 or earlier
The following script switches to a specific layout, pastes the current user name, then switches to a different layout. Note that Insert Calculated Result only works when the field is on the active layout.
Go to Layout ["User Name Layout"]
Insert Calculated Result [Table1::UserNameField; Get(AccountName)]
Go to Layout ["Layout Number based on User Name"]
Related topics 
Defining calculation fields
Script steps reference (alphabetical list)
Script steps reference (category list)