In the Position Sizing lesson, it mentions the following:

Lastly, we multiply the value per pip by a known unit/pip value ratio of EUR/USD. In this case, with 10k units (or one mini lot), each pip move is worth USD 1.

USD 0.25 per pip * [(10k units of EUR/USD)/(USD 1 per pip)] = 2,500 units of EUR/USD

Where do we get this [(10k units of EUR/USD)/(USD 1 per pip)] from? Is it static or does it change?

What if my account currency is neither the base or counter currency? In my case my account currency will be AUD and I’m looking at trading USDJPY. So confusing!

Thanks