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. Første nyttårsdag : Thursday, 1 January, 1981
2. Skjærtorsdag : Thursday, 16 April, 1981
3. Langfredag : Friday, 17 April, 1981
4. Andre påskedag : Monday, 20 April, 1981
5. Første mai : Friday, 1 May, 1981
6. Kristi Himmelfartsdag : Thursday, 28 May, 1981
7. Andre pinsedag : Monday, 8 June, 1981
8. Første Juledag : Friday, 25 December, 1981

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

1. Første påskedag : Sunday, 19 April, 1981
2. Grunnlovsdagen : Sunday, 17 May, 1981
3. Første pinsedag : Sunday, 7 June, 1981
4. Andre Juledag : Saturday, 26 December, 1981