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. New Year's Day : Tuesday, 1 January, 1980
2. Easter Monday : Monday, 7 April, 1980
3. Labor Day : Thursday, 1 May, 1980
4. Ascension Day : Thursday, 15 May, 1980
5. Pentecost Monday : Monday, 26 May, 1980
6. National Day : Monday, 21 July, 1980
7. Assumption of Mary : Friday, 15 August, 1980
8. Armistice Day : Tuesday, 11 November, 1980
9. Christmas Day : Thursday, 25 December, 1980

And here is the public holiday falling on a weekend:

1. All Saints' Day : Saturday, 1 November, 1980