The Gregorian calendar year begins January 1st, ends December 31st, and normally consists of 365 days unless it happens to be a leap year, which is an intercalary year with 366 days that occurs every 4 years except in the rare case where the year is divisible by 400.¹⁾

In a common year, the year starts and ends on the same day of the week, which makes that specific day of the week have 53 days while the other six days of the week have 52 days each. In a leap year, the year instead ends on the day of the week after the day of the week it starts on, which creates two days of the week that have 53 days each while the other five days of the week have 52 days each.

The art of reusing old calendars is simple. First, determine the day of the week the calendar starts on, then determine if the calendar year was a common year or a leap year. A chart is provided to show which calendars from certain years can be reused in other years. Unfortunately, the curator of this chart is currently mortal, so it will only cover the 20th, 21st, and 22nd centuries.

The majority of businesses in the United States observe, at the very least, six paid holidays which are as follows: New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving, and Christmas. Three of these holidays are static in the day of the week they occur on, two of them affected by the 1969 Uniform Monday Holiday Act, while the other three holidays vary by year.

Friday the 13th is considered to be an unlucky day according to western superstition. The following chart is just meant to be a visual representation of the years they occur on.

• I wanted to see if I could adjust my work schedule with the information from the six paid U.S. holidays section, but it wasn't very useful or I didn't see anything I wasn't willing to do.