Define a period

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How many working days in year 1981?

Here is the detail of the calculation:

Because 1981 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 8 public holidays that do not fall during a weekend and we obtain 253 working days in 1981.

Here is the list of these 8 public holidays:

1. Pesach : Sunday, 19 April, 1981
2. Yom Ha-Atzmaut : Thursday, 7 May, 1981
3. Shavuot : Monday, 8 June, 1981
4. Rosh Hashanah : Tuesday, 29 September, 1981
5. Rosh Hashanah : Wednesday, 30 September, 1981
6. Yom Kippur : Thursday, 8 October, 1981
7. Sukkot : Tuesday, 13 October, 1981
8. Shemini Atzeret / Simchat Torah : Tuesday, 20 October, 1981

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

1. Purim : Friday, 20 March, 1981
2. Shvi'i shel Pesach : Saturday, 25 April, 1981