Define a period

...

How many working days in year 1920?

Here is the detail of the calculation:

Because 1920 is a leap year, it has 366 days.

Let's remove 52 saturdays and 52 sundays. It remains 262 days.

Now, let's remove 11 public holidays that do not fall during a weekend and we obtain 251 working days in 1920.

Here is the list of these 11 public holidays:

1. New Year's Day : Thursday, 1 January, 1920
2. Day after New Year's Day : Friday, 2 January, 1920
3. Auckland Day : Monday, 26 January, 1920
4. Waitangi Day : Friday, 6 February, 1920
5. Good Friday : Friday, 2 April, 1920
6. Easter Monday : Monday, 5 April, 1920
7. Anzac Day Observance : Monday, 26 April, 1920
8. Queen's Birthday : Monday, 7 June, 1920
9. Labour Day : Monday, 25 October, 1920
10. Christmas Day Observance : Monday, 27 December, 1920
11. Boxing Day Observance : Tuesday, 28 December, 1920

And here are the 3 public holidays falling on a weekend:

1. Anzac Day : Sunday, 25 April, 1920
2. Christmas Day : Saturday, 25 December, 1920
3. Boxing Day : Sunday, 26 December, 1920