ARGENTINA:
The official currency in Argentina is the peso (AR$), made up of 100 centavos. Notes are in denominations of 2, 5, 10, 20, 50, 100 and 500. Coins are in denominations of 1 and 2 pesos, and 1, 5, 10, 25 and 50 centavos. Foreign currencies can be exchanged in banks and authorized cambios (bureaux de change) which are available in all major cities.
Most major credit cards are accepted, but not as widely as some other parts of the world.
ATMs are available in most cities, but it is advised to carry alternative forms of payment as daily withdrawal limits are low and machines don't always work.
CHILE:
The official currency in Chile is the Chilean peso (CLP. One peso is technically divided into 100 centavos, but due to inflation centavos are practically obsolete. Coins currently in circulation come in denominations of 10, 50, 100 and 500 pesos. 1 and 5 pesos coins can still be found, but are no longer produced. Bank notes in circulation come in denominations of 1000, 2000, 5000, 10000 and 20000 pesos. Foreign currencies can be exchanged in banks and casa de cambio (currency exchange).
Major credit and debit cards are widely accepted. Smaller shops, kiosks, markets and restaurants in remote areas may only accept cash.
ATMs are widely available in all major towns and cities and in the Santiago airport. The withdrawal limit is approximately 200,000 pesos per transaction (about $305 USD).