How does Penrose fool the suitors

Penelope was weaving a blanket and told the suitors that she would marry them when she finished. However, every night, she would undo the weaving from the previous day.

Okay so the way Penelope fooled her suitors was that she would marry them only when she finished weaving a blanket. However, she would unravel whatever she would have done during the day at night and that's how she kept them off.