Solution 19069: Finding Days Between Dates on the TI-83 Family, TI-84 Plus Family, or TI-Nspire™ in TI-84 Plus Mode.
How can I find the days between dates using the Finance App on TI-83 family, TI-84 Plus family or TI-Nspire Handheld in TI-84 Plus Mode calculators?To calculate the number of days between two dates using the actual-day-count method, use the date function dbd() or "days between dates". date1 and date2 can be numbers or lists of numbers within the range of the dates on a standard calendar. The dbd() function is found by accessing the Finance App and selecting option D. The syntax is as follows:
Please Note: Dates must be between the years 1950 through 2049.
date1 and date2 can be entered in either of the two formats below:
• MM.DDYY United States
• DDMM.YY Europe
For example, to find the number of days between 12/20/1988 and 12/20/2006:
1) Press [APPS]  [ALPHA] [D]. On the TI-83 press [2nd] [FINANCE] [ALPHA] [D].
2) Press   [.]     [,].
3) Press   [.]     [)].
4) Press [ENTER].
Please see the TI-83 family and TI-84 Plus family guidebooks for additional information.
Please Note: TI-Nspire users in TI-84 Plus mode may refer to the TI-84 Plus family guidebook.