Define a period

...

How many working days in year 1975?

Here is the detail of the calculation:

Because 1975 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 5 public holidays that do not fall during a weekend and we obtain 256 working days in 1975.

Here is the list of these 5 public holidays:

1. פסח : Thursday, 27 March, 1975
2. שביעי של פסח : Wednesday, 2 April, 1975
3. יום העצמאות : Wednesday, 16 April, 1975
4. ראש השנה : Sunday, 7 September, 1975
5. יום כיפור : Monday, 15 September, 1975

And here are the 4 public holidays falling on a weekend:

1. שבועות : Friday, 16 May, 1975
2. ראש השנה : Saturday, 6 September, 1975
3. סוכות : Saturday, 20 September, 1975
4. שמחת תורה/שמיני עצרת : Saturday, 27 September, 1975