How long does a knot have to be tied to be considered a "קשר של קימא". (Knot of permanence).
דבר דבר (Dabair Davar): Calculations for a סעודת מצוה Seudas Mitzvah;
How to Remove Gum, Paste, or Sticky Substances; Walking with High Heels on a Dirt Ground; Removing Twigs, Pebbles, etc. with One's Foot;
Writing with something permanent on a material that is permanent.