I say, and with God's success: Our Sheikh Al-Othmani said in the jurisprudence of sales (691-713): "The paper currencies issued in many countries today do not contain any wording indicating that they are debt instruments, so there is no issue in this regard, as they are one hundred percent conventional prices. As for the countries that still write such a promise on the notes, such as the British pound and the Pakistani and Indian rupees, this written promise today only expresses the central bank's guarantee to the holder to maintain the nominal value of the paper.... They are customary or conventional prices like circulating money, and the currency of each country is an independent type, thus zakat is obligatory on them and can be paid with them, and they may be capital in a salam contract, and riba applies to them, as if they are sold for their type, equality in value is required and immediate exchange in the session is obligatory... Exchanging banknotes issued by the same state is only permissible on the condition of their equivalence, and it is not permissible to have a difference in value among them. The equivalence here is not in the number of notes, but in the notional number of the notes represented by the value of the nominal notes. It is permissible to sell one note with a nominal value of fifty rupees for five notes, each with a nominal value of ten rupees; because the total value of these five equals fifty rupees, and this is not a consideration of value in equivalences, but the intended equivalence is in the number; because they are notional prices, and the notional price is a reality established by custom and consideration. The custom regarding these notes has made the ten-note equivalent in number to ten notes, so the nominal value is this notional number, and equality in that notional number is required. Ahmed Al-Zarqa said: "What appears is that the paper currency now called the Syrian currency circulating in our country is equivalent to that circulating in other countries, and it is considered among the circulating money. What was said about it from the previous rulings applies to it; because circulating money is what is made from materials other than the two metals, gold and silver, and it has been customary to use it like the two metals, and the mentioned paper is of this kind. Whoever claims to restrict circulating money to that made from metals must provide evidence for that," and God knows best.