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October 13. So the note does contain enough information for us to be able to determine
the interest, and then add it to the principal to arrive at the maturity value.
Counting the days takes some work. There are 3 days remaining in March, plus all of April
(30 days), May (31), June (30), July (31), August (31), September (30) and then the first 13 days
of October. Totaling these gives a term of 3 30 31 30 31 31 30 13 199 days.^7
While counting like this is not exactly difficult, it is tedious, and it would not be hard to acciden-
tally miscount the number of days in a month or leave out a month in the counting.
Matters would be much simpler if the note’s date and maturity date fell in the same
month. If the loan were made on January 4 and came due on January 25, we could just find
the difference by subtracting 25 4 21 days. But unfortunately just subtracting like this
won’t work when the two dates fall in different months.
The problem lies in that the day numbers are reset at the end of each month. After
January 31 comes February 1, not January 32. So if a loan is made on January 4 and comes
due on February 1, we can’t just subtract the way we did when both dates fell in the same
month. However, if we think of February 1 as January 32, then we could take 32 4
28 days. This approach is not as silly as it sounds. February 1 is not really January 32, but
it is the 32nd day of the year. So if we think of January 4 as day 4 and February 1 as day
32, the subtraction approach would make perfect sense and work just fine.
A date given as the day of the year without using any month name is sometimes called
an ordinal date, or a Julian date.^8 Since February 1 is the 32nd day of the year, February 1
would have an ordinal (Julian) date of 32.
Knowing the ordinal (Julian) dates for ordinary calendar dates can solve our problem
with finding a note’s term. March 28 happens to be the 87th day of the year, and October
13th is the 286th day of the year. Knowing this, we could find the term of Spencer’s loan
by subtracting: 286 87 199 days.
Of course, this raises the question of how we are supposed to know what day of the year
each date is. A day of the year table like Table 1.3.1 is a helpful tool that can come to our
rescue here.
This table doesn’t do anything for us that we couldn’t have done ourselves by count-
ing, but it saves the time and effort of doing so. To find out what day of the year March 28
is, we need only look in the March column and 28th row to find that it is day 87. To find
October 13, we just look in the October column and 13th row to see that October 13 is
day 286.
The following example will provide another illustration of how this table can be used.Example 1.4.1 Find the number of days between April 7, 2003, and September 23,
2003.Looking in the table, we see that April 7 is day 97, and September 23 is day 266. So there
are 266 97 169 days between those two dates.This table can obviously be quite handy when you need to do these kinds of calculations.
If you need the table and don’t have a copy of it handy, you can find ordinal (Julian) dates
by building and using an abbreviated version of this table. The key is to create a table that lists
the cumulative total number of days that have passed at the end of each month. January has
31 days, and so at the end of January a total of 31 days have passed in the year. February has 28
days (assuming the year is not a leap year) and so at the end of February a total of 31 28
59 days have passed. Likewise, March adds 31, so at the end of March 59 31 90 days have
passed. Continuing on in this way you can construct a table like Table 1.3.2.1.4 Promissory Notes 33(^7) One way to keep track of how many days each month has is to make fi sts with both hands. Recite the names
of the months while moving across your knuckles and the spaces between. January rests on the fi rst knuckle,
February on the space between fi rst and second knuckles, March on the second knuckle, and so on. The knuckle
months have 31 days, the between-knuckle months don’t (30 for all except February.)
(^8) Some object to calling this the Julian date, insisting that technically speaking a Julian date is the number of days
since January 1 of 4713 B.C.E. The Julian date for July 8, 2006, for example, would be 2453925. Nonetheless, the
use of the term as we have defi ned it is widespread, and so while we take no position on whether or not the term
should be used in this way, we recognize the fact that it commonly is used in this way.