HP HP-18C - Determining Past or Future Dates; Clearing the Date Arithmetic Variables

Determining Past or Future Dates
The HP-18C can determine the date a specified number of days from
another date using the actual calendar . To calculate a date :
1. Key in the known date in the current date format and press
1iDII ·
2. Key in the number of days. If the unknown date precedes the
known date, press ~. Press 1iDIiI.
3. Press 1mIIiI.
Example: Determining a future date. On February 9, 1987, you
purchase a 120-day option on a piece of land . Determine the expira-
tion date. Assume the date format is month/day/year .
Starting from the MAIN menu:
Keys:
IIIB ..
2.091987
IiDII
120 IiDIiI
Display:
DATE1=
2 .. ···09/ 1987 MO~~
Description:
Displays the CALC menu .
Stores DATE!.
ACTUAL DAYS= 120,00 Stores the number of
days in the future.
DATE 2 =
6/09 ..... 1987
TUE
Calculates the expiration
date.
Clearing the Date Arithmetic Variables
When the HP-18C is displaying the CALC menu, pressing
.1 CLEAR ALL I clears DATE1, DATE2, ACTUAL DAYS, 360 DAYS, and
365 DAYS to O. The date arithmetic variables are also cleared when-
ever you press .. in the TIME menu .
126 8: Time, Alarms, and Date Arithmetic