How many holidays are there in November and December if November 1 falls on a…

Concept: To count holidays across months, first fix the weekday of the 1st of each month using the 'odd days' rule - the days beyond complete weeks (days mod 7) shift the weekday forward by that many days. Once each month's 1st is fixed, list which dates are Sundays, and separately identify which dates are the 2nd and 4th Saturday, since only those two Saturdays are holidays, not every Saturday.

1. November 1 is a Tuesday. November has 30 days, i.e. 4 complete weeks plus 2 odd days, so December 1 falls 2 weekdays after Tuesday - a Thursday.

2. With November 1 a Tuesday, the Sundays in November fall on the 6th, 13th, 20th and 27th - 4 Sundays.

3. The Saturdays in November fall on the 5th, 12th, 19th and 26th, so the 2nd Saturday is the 12th and the 4th Saturday is the 26th - 2 more holidays.

4. November therefore has 4 + 2 = 6 holidays.

5. With December 1 a Thursday, the Sundays in December fall on the 4th, 11th, 18th and 25th - 4 Sundays.

6. The Saturdays in December fall on the 3rd, 10th, 17th, 24th and 31st, so the 2nd Saturday is the 10th and the 4th Saturday is the 24th - 2 more holidays.

7. December therefore also has 4 + 2 = 6 holidays.

8. Adding both months' totals gives 6 + 6 = 12 holidays across November and December combined.

Cross-check: assigning Sunday = 0 through Saturday = 6, Tuesday = 2. Adding 30 days for November gives (2 + 30) mod 7 = 4, which is Thursday - confirming December 1 independently of the odd-days count above.