Ajuda do LibreOffice 25.2
Returns the day of the week for the given date value. The day is returned as an integer between 1 (Sunday) and 7 (Saturday) if no type or type=1 is specified. For other types, see the table below.
WEEKDAY(Number [; Type])
número, como valor de data, é um valor decimal para o qual o dia da semana deve ser devolvido.
Type is optional and determines the type of calculation.
| Tipo | Weekday number returned | 
|---|---|
| 1 ou omisso | 1 (domingo) até 7 (sábado). Para compatibilidade com o Microsoft Excel. | 
| 2 | 1 (domingo) até 7 (sábado). | 
| 3 | 0 (segunda-feira) até 6 (domingo) | 
| 11 | 1 (segunda-feira) até 7 (domingo). | 
| 12 | 1 (terça-feira) até 7 (segunda-feira). | 
| 13 | 1 (quarta-feira) até 7 (terça-feira). | 
| 14 | 1 (quinta-feira) até 7 (quarta-feira). | 
| 15 | 1 (sexta-feira) até 7 (quinta-feira). | 
| 16 | 1 (sábado) até 7 (sexta-feira). | 
| 17 | 1 (domingo) até 7 (sábado). | 
These values apply only to the standard date format that you select under .
=WEEKDAY("2000-06-14") returns 4 (the Type parameter is missing, therefore the standard count is used. The standard count starts with Sunday as day number 1. June 14, 2000 was a Wednesday and therefore day number 4).
=WEEKDAY("1996-07-24";2) returns 3 (the Type parameter is 2, therefore Monday is day number 1. July 24, 1996 was a Wednesday and therefore day number 3).
=WEEKDAY("1996-07-24";1) returns 4 (the Type parameter is 1, therefore Sunday is day number 1. July 24, 1996 was a Wednesday and therefore day number 4).
=WEEKDAY("2017-05-02";14) returns 6 (the Type parameter is 14, therefore Thursday is day number 1. May 2, 2017 was a Tuesday and therefore day number 6)
=WEEKDAY(NOW()) returns the number of the current day.
To obtain a function indicating whether a day in A1 is a business day, use the IF and WEEKDAY functions as follows: 
IF(WEEKDAY(A1;2)<6;"Business day";"Weekend")