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 9 public holidays that do not fall during a weekend and we obtain 253 working days in 1980.

Here is the list of these 9 public holidays:

1. Nieuwjaarsdag : Tuesday, 1 January, 1980
2. Paasmaandag : Monday, 7 April, 1980
3. Dag van de Arbeid : Thursday, 1 May, 1980
4. Hemelvaartsdag : Thursday, 15 May, 1980
5. Pinkstermaandag : Monday, 26 May, 1980
6. Nationale Feestdag : Monday, 21 July, 1980
7. Onze-Lieve-Vrouw Hemelvaart : Friday, 15 August, 1980
8. Wapenstilstand : Tuesday, 11 November, 1980
9. Kerstmis : Thursday, 25 December, 1980

And here is the public holiday falling on a weekend:

1. Allerheiligen : Saturday, 1 November, 1980