Feeding Exchange Rate into Numbers

Hi,

I'm creating a Position Size Calculator in Numbers to manage my risk in the trading game. Most trading instruments are denominated in foreign currencies and to work out what I'm risking in Australian dollars, I need exchange rate feed into numbers to calculate from. Most of the time it would be calculating the exchange rate between Australia and United States. Otherwise I would have to manually input the exchange rate.

Is it possible to do this, if so how? I'm guessing a site like Yahoo Finance would be used!

Thanks in advance ...

Graeme