system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] What is the conversion rate between muggle money and wizard money?

A thought struck me, how do muggle born children like Hermione buy their books and school supplies for Hogwarts?
gpt
I'll tell you what it is, for anyone who can move between the Muggle and Wizard worlds: an opportunity to make a *killing*, thanks to a magical power few wizards have ever mastered: the power of commodities trading.

One Galleon is worth exactly 17 Sickles; or, to be a bit more precise, one Galleon's worth of gold is worth exactly 17 Sickles worth of silver. No more, no less. Many wizards assume this is the same as in muggle currency, where, for example, one dollar is worth exactly 100 cents. But there is a key difference. Muggle money, in and of itself, is worthless; it is a medium of exchange, but has no value on its own. Gold and silver, on the other hand, *do* have their own value, and in the muggle world, they are independent of each other. On one day, one Galleon's worth of gold might be worth 17 Sickle's worth of silver; on another, it might be worth 16, or 18, or 20.

So what does this mean for the enterprising witch or wizard? Well, one could walk into Gringotts with 10 Galleons, and ask for change; the goblins there are perfectly happy to provide 170 Sickles in exchange. The wizard could then stroll out of the Leaky Cauldron into the muggle world, and sell the Sickles for *11 Galleons* worth of gold. Or perhaps he sold 150 Sickles for 10 Galleons. Either way, our witch or wizard made a tidy profit with nothing but a little buying and selling. No trickery necessary. And what should he or she do with her profit? Why, turn right around and do it again.