## 1961 1967 1972 1978

You now have all the information necessary to do the calendar stunt, except for one thing. If it is a leap year and the date you are interested in is for either January or February —then the day of the week will be one day earlier than what your calculations tell you. For example:— If you wanted to find the day of the week for February 15th, 1944:— The key for 1944 is 6- Add this to the key for February, which is 4, to get a total of 10. Remove the seven, leaving 3. Add the 3 to the day minus the sevens, (15th day minus 14) which is 3 plus one, giving you a final total of 4. Four would ordinarily represent Wednesday, but in this case, you know that it is actually one day earlier, or Tuesday.

Remember that you do this only for January and February of a leap year. You can tell if a year is a leap year by dividing four into the last two digits. If four goes in evenly, with no remainder, then it is a leap year. (1944—4 into 44 is 11, no remainder). The year 1900 is not a leap year.

Two more examples of the system:—

June 2, 1923 — 0 plus 5 is 5 5 plus 2 is 7 7 minus 7 is 0 0 is Saturday.

5 plus 29 is 34

6 is Friday.

See if you can find the day of the week for the following dates:— September 9, 1906, January 18, 1916 (leap year), August 20, 1974, March 12, 1931 and December 25, 1921.

I don't intend to tell you that this system is a snap to learn to do quickly; it does take some time and study, but, as I'm sure most of you know—nothing worthwhile comes too easily.

By the way, if you like this idea better than the one at the beginning of this chapter, and would like to use it for practical purposes—you could remember the "year keys" of only the years you're interested in. That might be the previous year, the present year and the following year. With that, and your "month keys," you would be able to know the day of the week for any date within those three years.

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