Your base currency is NLG. You have created a purchase order for 40 filters at 7 USD each from a company in the United States. The price of US filters must first be converted to EUR, then to NLG. Assuming the exchange rates are 1.2 USD-EUR and 2.4 NLG-EUR, Datastream 7i calculates the following conversion:
40 filters @ 7 USD = 280 USD;
280 USD/1.2 = 233.33 EUR;
233.33 EUR x 2.4 = 560 NLG