Your base currency is USD. You have created a purchase order for 50 filters at 6 NLG each from a company in the Netherlands. The price of the Dutch filters must first be converted to EUR, then to USD. Assuming that the exchange rates are 2.4 NLG-EUR, and 0.8 EUR-USD, Datastream 7i calculates the following conversion:
30 filters @ 6 NLG = 180 NLG;
180 NLG/2.4 = 75 EUR;
75 EUR/0.8 = 93.75 USD