## 1905 1911 1916 1922 1933 1939 1944 1950 1961 1967 1972 1978

How does this system work? Well, for once the answer is that it is not completely easy although 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 represented 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 i.

In order to check this system, we will take a couple of examples, one from a recent year, and one which if you have bought this book before the end of 1972, will be a day in the future.

The day we will try to hunt down is the 19th 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 week which is a Wednesday!

The date in the future we shall be concerned with is August 23rd 1972. Our key number for August is 3 which we add to 23 giving 26. The key number for the year 1972 is 6 which added to 26 gives us a total of 32. Subtracting all the sevens (4x7 = 28) from 32 we arrive at 4. The 4th day of the week is a Wednesday which is the day for August 23rd, 1972!

The only exception to this rule occurs in leap years, and then only in the months of January and February. Your calculations will be identical but for these two months only the day of the week will be one day earlier than the day you calculate.

As with other systems the best way to gain confidence with those discussed in this chapter is to practise them. I suggest that you start with the easier of the two first, become skilled in it, and then graduate to the more advanced. Both of these systems are excellent for entertaining your friends and social acquaintances.

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