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USE YOUR MEMORY
Suppose you wish to know the final day of the year. The process
is similar. Knowing that the first Sunday of the last month falls on
the 5th day, you add the three sevens representing the following
Sundays to arrive at Sunday 26th. Reciting the next few dates and
days we get: 27th Monday; 28th Tuesday; 29th Wednesday; 30th
Thursday; 31st (the last day of the year) - a Friday.
As you can see, this system can be applied to any year for which
you may especially need to know days for dates. All you have to do
is to make up a Memory Number for the first Sunday or, for that
matter, the first Monday, Tuesday, etc., of each month of the year;
add sevens where appropriate to bring you near to the day in
question; and recite to that day.
An interesting tip in making use of the Memory Number of one
year with relation to surrounding years is that with each year the
first date for the days at the beginning of the month goes down
one, with the exception of leap years, when the extra day produces
a jump of two for the following year. In the years 1969, 1970,
1971, for instance, the first Sunday for January fell respectively on
the 5th, 4th and 3rd days of the month.
The second of the two systems to be introduced in this chapter is
for calculating the day for any date from 1900 to 2000. It is
necessary in this system to ascribe to each month a number that
will always remain the same. The numbers for the months are as
follows:
Some people suggest that these be remembered using associa-
tions such as January is the first month, the fourth letter in
February is r, which represents 4, and so on, but I think that it is
better to use the number:
I2O
January 1
February 4
March 4
April 0
May 2
June 5
July 0
August 3
September 6
October 1
November 4
December 6
MEMORY SYSTEM FOR DATES IN OUR CENTURY
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making the words DRaweR, SNaiL, SMaSH and THRuSH.
These can then be linked by imagining a drawer on which a snail's
shell is smashed by a thrush. In this way the key numbers for the
months can be remembered.
In addition to the key numbers for the months, the years
themselves have key numbers, and I have listed them, from 1900
to 2000.
This system is not so easy to master, but with a little practice it can
become almost second nature. The method is as follows: given the
month, numerical date and the year, you add the number repre-
sented by the month key to the number of the date, and add this
total to the key number representing the year in question. From
the total you subtract all the sevens, and the remaining number
represents the day in the week, taking Sunday as day 1. If the total
is exactly divisible by 7, e.g. 28, subtract one less 7 (in this case 3 x
7 = 21 instead of 4 x 7 = 28).
In order to check this system, we will take a couple of examples.
The day we will try to hunt down is 19 March 1969. Our key
number for March is 4, which we must then add to the date in
question, which is 19: 19 + 4 = 23. To this total we must add the
key number for the year 1969. Referring to the list we find that this
is 2. Adding 2 to our previous total we arrive at 23 + 2 = 25.
Subtracting all the sevens from this (3 x 7 = 21) we arrive at 25 —
21 = 4. The day in question is consequently the 4th day of the
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