Define a period

...

How many working days in year 1991?

Here is the detail of the calculation:

Because 1991 is not a leap year, it has 365 days.

Let's remove 52 saturdays and 52 sundays. It remains 261 days.

Now, let's remove 9 public holidays that do not fall during a weekend and we obtain 252 working days in 1991.

Here is the list of these 9 public holidays:

1. New Year's Day : Tuesday, 1 January, 1991
2. Easter Monday : Monday, 1 April, 1991
3. Labour Day : Wednesday, 1 May, 1991
4. Ascension Day : Thursday, 9 May, 1991
5. Whit Monday : Monday, 20 May, 1991
6. Assumption of Mary : Thursday, 15 August, 1991
7. All Saints' Day : Friday, 1 November, 1991
8. Christmas Day : Wednesday, 25 December, 1991
9. St. Stephen's Day : Thursday, 26 December, 1991

And here is the public holiday falling on a weekend:

1. National Day : Sunday, 23 June, 1991