I have a very simple question that came into my mind just now.
When you use money unit like dollar and pound, you use plural like dollars and pounds, but for foreign currency, you don’t use plural. You don’t say 100 yens, for example.
Is there any reason for it or is it just customary ?
The singular and plural forms of some currencies, such as the yen, are the same.
Some currencies, like Japan’s yen, have the same word for the singular and plural forms.