A galleon is seventeen sickles and a sickle is twenty nine knuts.
Three questions:
1) Why couldn’t they use easy numbers instead of seventeen and twenty nine?
2) The first description of Harry’s vault is: “Inside were mounds of gold coins. Columns of silver. Heaps of little bronze Knuts.” Why didn’t Harry’s parents trade in their heaps of knuts and columns of silver for some galleons?
3) (This one is the real question.) “A plump woman outside an Apothecary was shaking her head as they passed, saying, ‘Dragon liver, seventeen Sickles an ounce, they’re mad….'”