The Iranian valuta is quite complicated to use. This is why:
1) You can not withdraw money in Iran
First of all you can not withdraw any money as a foreigner. You can only change your dollars or euros which you should take from another country into Iran.
2) Black market exchange rate in Iran
There is an ‘official’ exchange rate used by banks and official institutes. But it’s almost 3 times worse than the ‘black market’ exchange rate. Everybody uses the black marker exchange rate and of course we exchanged our money at some black market rate.
3) Prices are shown in Toman but you pay with Rials
Most prices will be shown in ‘Toman’ which is the old currency of Iran. Nowadays you pay with ‘Rial’. The difference is a zero. So if they tell you something is 14.000 Toman (about 1 euro), than you should pay 140.000 Rials
4) Farsi Language
Prices are shown in Farsi (Language of Iran). The Farsi numbers look totally different than the Latin numbers we are used to.