How to create an online currency exchange counter?

Question

Payment systems

Good evening, dear programmers, you need to solve the problem, there is a virtual currency that is equal to one gram of gold, you need to create a website on which the exchange rate will change in real time, which will be calculated from the formula:
VirtualCurrency = Exchange rate of gold in real time (it is quoted in troy ounces, in order to convert to grams, you need to divide by 31.1) = the exchange rate in dollars, here is an example:
VirtualCurrency = $1200/31.1(g) = $38.58 for one virtual currency.
Tell me in which direction to dig, or the name of the script, I will be very grateful.

Answer 1

jsfiddle.net/L4j4f3qs