When a currency pair is written it is always followed by two numbers, the numerical value of the first is always smaller than the second. EUR / USD Bid: 1.3428 | Ask: 1.3431. When transaction, all trades are performed in the nominal value of the base currency. For example someone wants to trade in EUR / USD, the amount will be $ 100,000 in euros and not in dollars. The terminology will sell $ 100,000 euros against dollars selling price (bid) or buy $ 100,00 euros against dollars to the purchase price (ask) The number represents the amount of the second currency we need to share and receive one unit of the base currency. If one seeks to gain EUR / USD purchase price (1,3431 for example) means that you need to buy $ 1,34 1 euro.