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 7 public holidays that do not fall during a weekend and we obtain 254 working days in 1991.

Here is the list of these 7 public holidays:

1. יום העצמאות : Thursday, 18 April, 1991
2. שבועות : Sunday, 19 May, 1991
3. ראש השנה : Monday, 9 September, 1991
4. ראש השנה : Tuesday, 10 September, 1991
5. יום כיפור : Wednesday, 18 September, 1991
6. סוכות : Monday, 23 September, 1991
7. שמחת תורה/שמיני עצרת : Monday, 30 September, 1991

And here are the 2 public holidays falling on a weekend:

1. פסח : Saturday, 30 March, 1991
2. שביעי של פסח : Friday, 5 April, 1991