
An annual rate of interest is converted to a daily rate of interest by dividing by the number of days in the year.
The computer will calculate this value to at least 14 decimal places, but you can set here the rules for rounding the figure into a more manageable format.
See Rounding of Interest Rates for an explanation of each option. That setting controls rounding of the annual rate of interest whereas this one controls rounding of the daily rate.