200C

Dilution used on a homeopathic preparation called Occilococcinum, made from freeze-dried powdered duck liver diluted one hundredfold in solvent 200 times over and supposedly of use in curing cold and flu symptoms. This dilution, if accurately labelled, would represent one molecule of (allegedly) active ingredient in 1 followed by 400 zeroes other molecules, or in other words somewhere between the fourth and fifth exponential powers of the total number of atoms in the observable Universe.