Define a period

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How many working days in year 1957?

Here is the detail of the calculation:

Because 1957 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 9 public holidays that do not fall during a weekend and we obtain 252 working days in 1957.

Here is the list of these 9 public holidays:

1. Año Nuevo : Tuesday, 1 January, 1957
2. Jueves Santo : Thursday, 18 April, 1957
3. Viernes Santo : Friday, 19 April, 1957
4. Día del Trabajo : Wednesday, 1 May, 1957
5. Día del Ejército : Monday, 1 July, 1957
6. Día de Todos los Santos : Friday, 1 November, 1957
7. Noche Buena : Tuesday, 24 December, 1957
8. Navidad : Wednesday, 25 December, 1957
9. Víspera de Año Nuevo : Tuesday, 31 December, 1957

And here are the 3 public holidays falling on a weekend:

1. Sábado Santo : Saturday, 20 April, 1957
2. Día de la Independencia : Sunday, 15 September, 1957
3. Día de la Revolución : Sunday, 20 October, 1957