A graph would probably do it.
Also I have a hard time believing that someone is selling 500BTC for .225 EUR
That's right at market rate. .225 * 1.32 = .297
Assuming I base the EUR prices on USD conversion which is not the case, EUR prices are fixed by the market, there is no EUR -> USD conversion whatsoever.
The price is for one BTC, not for the complete amount, 500 BTC would then sell at 112.50 EUR @ .225 EUR/BTC