How would calculate the exchange rate of Bitcoin GBP

Question

I've got an API that returns the value of USD/Bitcoin & USD/GBP.

{"USDBITCOIN":"4251.27", "USDGBP":"0.758659"}

To calculate the exchange rate of GBP/Bitcoin, I simply divide the value of the GBP by Bitcoin, because they are both USD based.

How would calculate the exchange rate of Bitcoin/GBP? It may be really simple, but it's really baffling me. I've got the below to calculate

app.js

xOfy(unit, value) { return unit / value; } yOfX(unit, value) { return unit * value; } xOfy(gbp, bitcoin) // 0.00018 yOfx(bitcoin, gbp) // 3225.26

Answer 1

You simply divide 1 by the resulting value:

1 / (USDGBP * USDBITCOIN)

In this case, that'd be:

1 / (0.758659 * 4251.27) = 0.0003100521146296338

The 1 itself comes from the fact that 4251.27 USD is how much 1 Bitcoin is worth.