Returns the difference between two dates based on the 360 day year used in interest calculations.
DAYS360(Date1; Date2[; Type])
If Date_2 is earlier than Date_1, the function will return a negative number.
The optional argument Type determines the type of difference calculation. If Type = 0 or if the argument is missing, the US method (NASD, National Association of Securities Dealers) is used. If Type <> 0, the European method is used.
=DAYS360("2000-01-01";NOW()) returns the number of interest days from January 1, 2000 until today.