If you refer to some religious tradition, different religions (or religious groups) have different days reserved for fasting.
you have to fast for 40 days
13 days
He fasted for 36 days.. :)
Ramadhan
40 days of Lent.
114 days
Not fast at all! 5-14 days
No, there are no Catholic fast days during Advent. Ash Wednesday and Good Friday are the only fast days during the Liturgical Year.
'Ash Wednesday' and 'Good Friday' are the days of fast and penance.
88 Days(In earth days)
The Daniel fast lasted 3 weeks (21 days)
3 days