Take US Dollars or Euros with you to Iran and change them up into Iranian Rial at the local exchange offices (not the dodgy guys on the street or at the hotels which have the lower government exchange rate).
Before you know it, you have millions of Rials and it all looks easy. However,while ALL notes state ‘Rial’ there is another ‘currency’ or ‘super unit’ that is used – Toman – which is not listed on any note or coin.
Toman is simply one tenth of the Rial price.
Lost? It takes a couple of days to get used to, but in the majority of cases, unless stated clearly, all prices are in Toman and not Rial. Hence, the basic equation anywhere in Iran is to add a zero onto printed prices (if ‘Rial’ is not listed), or ask market vendors and others which ‘currency’ they are operating in to save the confusion.