Each language has its own rules
Writing numbers in words is not a word-for-word translation. English joins tens and units with a hyphen (twenty-one) and British English adds and after hundred (one hundred and one). German writes everything below a million as one word with the units first: 234 is zweihundertvierunddreißig. French counts 70 as sixty-ten (soixante-dix) and 80 as four-twenties (quatre-vingts), while Belgium and Switzerland say septante and nonante, and Switzerland also huitante. Vingt and cent take an s only at the end of a number.
Spanish and Portuguese change with gender (veintiuna, duzentas) and shorten before nouns (veintiún, un millón). Portuguese places e between parts in a specific way (mil e cem, but mil duzentos e trinta). Spanish and European Portuguese use the long scale, so a billón is a million millions. Turkish writes yüz and bin without bir (one) in front. The converter follows these rules, and the options appear only for the language that needs them.
Amounts for checks, invoices and contracts
In Amount mode the number is written the way it appears on a check or a contract: the whole part in words, followed by the cents either as 45/100 or in words. Type your currency yourself, for example dollar/dollars, euro/euros, peso/pesos or lira. When you write the singular and plural separated by a slash, the right form is used for one and for more than one. In Spanish, Portuguese and French, round millions get de before the currency (un millón de pesos, deux millions d'euros).
Amounts are rounded to two decimals. The Turkish option to write without spaces is common on Turkish checks, because joined words are harder to change afterwards.
Ordinal numbers
Ordinal mode writes first, second, twenty-first, hundredth and so on: erste and einundzwanzigste in German, premier, vingt et unième and quatre-vingtième in French, vigésimo primero in Spanish, vigésimo primeiro in Portuguese and yirmi birinci in Turkish. Spanish, Portuguese and French also have feminine forms (primera, primeira, première). German, Spanish and Portuguese ordinals are written up to 999,999, where everyday use ends.