Simplify the following text for a Grade 15 native English-speaking person.
Original: In many countries the ISO codes for the more common currencies are so well known publicly that exchange rates published in newspapers or posted in banks use only these to delineate the different currencies , instead of translated currency names or ambiguous currency symbols .
Simplified: In many countries , the codes for the more common currencies are so well-known , by the general public , that exchange rates written in newspapers or posted in banks use only those codes to define the different currencies , instead of translated currency names or currency symbols .