Hopefully I have posted this in the appropriate forum (this could probably go into the JS forum as well and if so, my apologies.)
I have a monthly mileage log that has a field where the user will enter the the beginning vehicle odometer reading (this is a MANDATORY FIELD) at the beginning of the month OR when the vehicle is first used.
I then have 31 fields underneath corresponding to the days in a month with each field containing the ENDING odometer reading for that day. If the vehicle wasn't used on a particular day, that day's field would be blank. At the very bottom would be a "total miles" field. As a example, the data would be like this:
Beginning Mileage: 111,111
TOTAL MILEAGE 2,989
"Total mileage" = "Beginning Mileage" MINUS "the odometer reading of the 31st day AKA the LAST ENTRY FOR THAT MONTH"
Therein lies my issue. How can I make the "total mileage" field be dynamic? Let's say the vehicle was only used from the 5th through the 10th, how can I have the "total mileage" field display the correct odometer reading?
Hopefully, I explained this well enough for someone to help me and all help will be greatly appreciated.