I'm sure you've seen code on Notes Net or elsewhere to take a date and adjust by a fixed number of business days. The code usually looks at the current day of the week and adjusts by the fixed number plus some offset. For example, if you want to adjust by 2 business days then if the starting date is Monday through Wednesday you adjust by 2 days, Thursday through Sunday is adjusted by 4 days.

Note that this formula does not account for holidays - that would add quite a bit to the complexity. Also note that the resulting day will ALWAYS be a Monday through Friday, no matter what you start with. For example, if you start with a Saturday and adjust by zero business days, you'll end up with the following Monday.

This formula assumes two things:
1. There is a field called Start that is the starting date (a date/time field).
2. There is a field called NumDays that has the number of business days to adjust (a number field).

NumFullWeeks := @Integer(NumDays / 5);
ExtraDays := NumDays - (NumFullWeeks * 5);
W1 := @Weekday(Start);
W2 := @Weekday(tempEndingDate);
AdjustValue := (NumFullWeeks * 7) + ExtraDays + @If(W1 > W2; 2; W1 = 1; 1; W1 = 7; 2; W2 = 1; 1; W2 = 7; 2; 0);