The Rial is the official currency used in Iran however the Toman is most commonly used in shops and bazaars.
A Toman is the equivalent of 10 Rials.
It can get a little confusing when you are handling large amounts of notes but hopefully this summary will help you a little.
The easiest way to calculate Toman to Rial is simply add a zero at the end of Rial.
1 Toman = 10 Rials
10 Toman = 100 Rials
100 Toman = 1000 Rials
1000 Toman = 10,000 Rials
IMPORTANT - Due to sanctions foreigners are unable to use the ATM machines in Iran. Please ensure you have brought enough money to cover your entire trip.
You can change your money in any bank in Iran but the quickest and most commonly used method is going to an exchange shop.