In Iran, the local currency is the Iranian Rial, IRR, but all traders and almost all Iranians speak in Tomans.
100,000 Rials = 10,000 tomans, just subtract a zero.
Iran’s currency fluctuates wildly and has soared for the past two years following political events, the election of Trump in the United States, the end of the nuclear deal and the consequences of that decision.
Due to international sanctions, it is not possible to use your bank card in Iran (except at certain merchants paired with a bank account located abroad). You will therefore have to withdraw Euros before departure. Remember to take more than not enough.
Once there you can change your money as you go in the exchange offices. Above all, do not change all of your money upon arrival, as the amount of banknotes that will be issued to you will be difficult to transport.
Be sure to change your money in official exchange offices and not hastily in the street to avoid being given counterfeit banknotes or other disappointments.
Moreover, exchange offices offer much more advantageous rates than in hotels.
Warning ! the exchange rate given on the official sites is different from that practiced locally!
At the airport the exchange rate is less attractive, so only change money for the taxi and the first charges on the spot.
There are also temporary credit card solutions that you can use for the duration of your stay.
Card payment is very common in Iran and very convenient.
The two “leaders” of this solution are Daric Pay Card and Mah Card.