Friday / Fri. = piątek, pt. (skrót)

Pocket Calendar Friday

Source: http://www.janbrett.com/pocket_calendar/pocket_calendar_thur_sat.htm

piątek, pt. (skrót)

Friday , Fri. = piątek, pt. (skrót)

English sentence and Polish translation

Sorry, but I have a maths test on Friday. = Przepraszam, ale w piątek mam test z matematyki.