As the title implies, when using the ArcGIS OnLine calculator it would be nice to apply calculations to selected records only.
I agree it would be useful and intuitive to be able to calculate selected records from the item details/data/table view page (and also from the attribute table in the map view).
A workaround that I just tested works as follows:
Yes please! It is quite clunky and a significant hurdle for teaching non-GIS folks to do very basic tasks, like tagging a "done" field for records that have been downloaded and post-processed.
Retrieving data ...