TI-83 Plus Tables and Reference Information 734
Actual/actual day-count method (assumes actual number of days per
month and actual number of days per year):
dbd( (days between dates) = Number of Days II - Number of Days I
Number of Days I = (Y1
-YB) × 365
+ (number of days MB to M1)
+DT1
+4
)1( YBY−
Number of Days II = (Y2
-YB) × 365
+ (number of days MB to M2)
+DT2
+4
)2( YBY−
where: M1= month of first date
DT1= day of first date
Y1= year of first date
M2= month of second date
DT2= day of second date
Y2= year of second date
MB = base month (January)
DB = base day (1)
YB = base year (first year after leap year)