Define a period

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How many working days in year 1990?

Here is the detail of the calculation:

Because 1990 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 7 public holidays that do not fall during a weekend and we obtain 254 working days in 1990.

Here is the list of these 7 public holidays:

1. Año Nuevo : Monday, 1 January, 1990
2. Día de la Constitución : Monday, 5 February, 1990
3. Natalicio de Benito Juárez : Monday, 19 March, 1990
4. Viernes Santo : Friday, 13 April, 1990
5. Día del Trabajo : Tuesday, 1 May, 1990
6. Día de la Revolución : Monday, 19 November, 1990
7. Navidad : Tuesday, 25 December, 1990

And here is the public holiday falling on a weekend:

1. Día de la Independencia : Sunday, 16 September, 1990