I am trying to add 2 time fields together to get a total time. Here are the 2 fields default values that I am adding together. The formula verifies but when I preview the form the field displays NaN.
concat(substring(100 + number(concat("0", substring(EndTime, 1, 2))) - number(concat("0", substring(EndTime, 1, 2))), 2, 2), ...