Date Arithmetic; Determining The Day Of The Week For Any Date - HP -18C Owner's Manual

Date Arithmetic
The CALC menu is used to do date arithmetic-finding the number of
days between two dates, or determining the date a given number of
days in the future or past. Date arithmetic uses one of three calen-
dars-actual, 365-day, or 360-day (refer to table 8-3). You can also
use the CALC menu to determine the day of the week for any date.
To display the CALC menu, from the MAIN menu, press
IIDlII,
then
BiB·
Table 8·3. The CALC Menu for Date Arithmetic
Menu Key Description
mIIII Stores or calculates a date, using the current date format-
IDIIB
month/day/year (MM.DDYYYY)
or
day. month. year
(DD.MMYYYY); also displays the day of the week. If you omit
YYYY, the calculator uses the current year.
Eil1iI
Stores or calculates the number of days between DATE1 and
DATE2, using the actual calendar. The actual calendar recog-
nizes leap years.
mmI Calculates the number of days between DATE1 and DATE2,
using the 36D-day calendar. The 36D-day calendar is based
on 3D-day months.
IEiJII
Calculates the number of days between DATE1 and DATE2,
using the 365-day calendar. The 365-day calendar ignores
leap years.
IIWliD
Displays the current date, which can then be stored in DATE1
or DATE2.
Determining the Day of the Week For Any Date
To find the day of the week for any date, key in the date and press
mIIII
or
IDIIB ·
124 8: Time, Alarms, and Date Arithmetic