access actual STORES time as fractional days
so 6 hrs is 0.25 days
so you can add time, to give a total, say 1,25 days.
however if you display it as time, it just shows the 6hrs, and not the days
if you display as a date it will sohw a date in 1900 or somesuch
if you display it as a number, it will show 1.25
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so add the values in the way you are doing, but make the text box which stores the total hidden
now have a separate number field, set to double, fixed, 2decimal points, say and just set the control source for this to be
=myhiddentimefield * 24
so if the time adds to 1.25 days, the visible textbox will show 30.00 hours (ie 1.25 * 24)
if you want to be fancy you can change the decimal fractions of hours to minutes in a similar way - so that 30.23 hours could become 30hours 14 minutes (say)