Texas Instruments TI-83 PLUS - Manual (Page 737)

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 ( YB Y
−
Number of Days II = ( Y2 - YB )
×
365
+ (number of days MB to M2 )
+ DT2
+
4
) 2 ( YB Y
−
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)