You want to use an expression along the idea of
count(group2) div field5
Where group2 is the repeating row and field5 is the text box they entered a
number into.

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> I’m designing a form with a repeating table into which users will enter a
> date. I’m not really interested so much in the actual date, but rather how
> many dates they enter. I want to take this number (i.e. the total number of
> rows, or the position of the last row in the table) and divide this by the
> total number of possible dates (entered manually into a textbox by the user)
> to calculate a percentage. Any ideas?