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 9 public holidays that do not fall during a weekend and we obtain 252 working days in 1981.

Here is the list of these 9 public holidays:

1. Solenidade da Santa Mãe de Deus : Thursday, 1 January, 1981
2. Sexta-Feira Santa : Friday, 17 April, 1981
3. Dia do Trabalhador : Friday, 1 May, 1981
4. Dia de Portugal : Wednesday, 10 June, 1981
5. Corpo de Deus : Thursday, 18 June, 1981
6. Implantação da República : Monday, 5 October, 1981
7. Restauração da Independência : Tuesday, 1 December, 1981
8. Dia da Imaculada Conceição : Tuesday, 8 December, 1981
9. Natal : Friday, 25 December, 1981

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

1. Páscoa : Sunday, 19 April, 1981
2. Dia da Liberdade : Saturday, 25 April, 1981
3. Assunção de Nossa Senhora : Saturday, 15 August, 1981
4. Todos os Santos : Sunday, 1 November, 1981