Define a period

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How many working days in year 1980?

Here is the detail of the calculation:

Because 1980 is a leap year, it has 366 days.

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

Now, let's remove 7 public holidays that do not fall during a weekend and we obtain 255 working days in 1980.

Here is the list of these 7 public holidays:

1. Pesach : Tuesday, 1 April, 1980
2. Shvi'i shel Pesach : Monday, 7 April, 1980
3. Yom Ha-Atzmaut : Monday, 21 April, 1980
4. Shavuot : Wednesday, 21 May, 1980
5. Rosh Hashanah : Thursday, 11 September, 1980
6. Sukkot : Thursday, 25 September, 1980
7. Shemini Atzeret / Simchat Torah : Thursday, 2 October, 1980

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

1. Rosh Hashanah : Friday, 12 September, 1980
2. Yom Kippur : Saturday, 20 September, 1980