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General Operating Instructions
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Calculating Time Intervals
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Another very useful function involves the  DAY
key. It will determine the number of calendar days between two
dates—ranging from January 1, 1900 to December 31,
2099—and will check for range and logic errors. An example of the
latter might be February 29, 1973 or February 30th of any year. An
erroneous date—whether a logic or range
error will cause the display to blink. The DAY key is used in much the same way as the other function keys except that the following convention must be observed:
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Enter the month number. Follow it with a decimal point, followed by a two-numeral day number, followed by the full year number.
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For example:
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May 11, 1973
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would be entered as
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5.111973
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June 3, 1984
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would be entered as
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6.031984
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November 9, 2009
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would be entered as
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11.092009
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Thus, to find the number of days between two dates, simply key in the first date and press SAVE , key in the second date and press DAY.
The answer, shown in
days, is ready for other operations or input to another problem. For
example, to find the exact number of days between December 10, 1974 and
March 14, 1976,
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| | Enter: | | | See Displayed: | | |
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| 12.101974 SAVE 3.141976 DAY | | | |
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number of days
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Calculating Future or Past Dates
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You can find a future or past date in the range January 1, 1900 to
December 31, 2099—given the number of days—without having to count
knuckles or remember
rhymes. (You don’t need to worry if the year entered is a leap year; leap year calculations are handled automatically.) Here’s how:
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If you want the year number to be displayed, set rounding for 6 decimal places by pressing the gold key and 6 (number key).
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Enter the starting date according to the date convention (above). Press SAVE .
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Enter the number of days (press CHS if you’re finding a past date).
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| 4 |
Press DAY (DATE).
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