"To see a ripe apple"
Translation:A vedea un măr copt
Long story short: yes, simply memorizing them all. Always learn gender + noun, instead of just the noun.
A / AN / ONE = UN / O and TWO = DOI / DOUĂ
In Romanian, the numerals "one" and "two" have two forms each: one for masculine and one for feminine. Starting from "three" the form is unique. So:
one = UN --- for masculine (and neuter*) nouns: one man = UN bărbat
one = O --- for feminine nouns: one woman = O femeie
two = DOI --- for masculine nouns: two men = DOI bărbați
two = DOUĂ --- for feminine (and neuter*) nouns: two women = DOUĂ femei
*The third gender (neuter) is a combination of singular masculine and plural feminine:
one apple = UN măr
two apples = DOUĂ mere
The indefinite article "a/an" also has two forms, one for masculine and one for feminine, and they are identical to the numerals:
a/an = UN --- for masculine nouns: a man = UN bărbat, and for neuter nouns: an apple = UN măr
a/an = O --- for feminine nouns: a woman = O femeie
Back in school, I learned that the easy and safe way to identify the gender of a noun is to count that noun. There are three genders and corresponding to them there are three different countings:
UN - DOI --- if the noun takes UN in singular and DOI in plural then it is MASCULINE
O - DOUĂ --- if the noun takes O in singular and DOUĂ in plural then it is FEMININE
UN - DOUĂ --- if the noun takes UN in singular and DOUĂ in plural then it is NEUTER
Of course, this assumes that you already know how to count a noun, which means you know what numerals that noun takes in singular and plural. Which a native already knows at school age, because he learned them until then (by immersion). You might want to know the gender first so you can infer the articles and numerals from it, but neither the natives follow that path. There are some patterns in noun endings that you can observe, but I would recommend not to learn them by heart because they are many and also because there are exceptions. Stick to learning gender + noun for a while, and your guessing will improve naturally.
You can find more information on the following Wiki page, including rules to determine the gender. Beware of the exceptions.