The fact that we can derive the British pound​/Israeli shekel exchange​ rate, say, from the ​dollar/pound rate and the ​dollar/shekel rate follows from ruling out a potentially profitable arbitrage strategy known as triangular arbitrage. As an example, suppose that the British pound price of a zloty was below the British pound price of a dollar times the dollar price of a zloty, as depicted by the hypothetical data in the following table. Exchange rate Value
British pound price of a zloty 4.0
British pound Vice of a dollar 1.60
U. S. dollar price of a zloty 5.00

Using $100 to purchase the Polish currency directly would obtain zlotys.