Latvian numbers are largely straightforward for English speakers, with one small but genuine grammatical wrinkle worth knowing from the start.
The number "one" changes form to match the gender of the noun it counts: viens (masculine) vs. viena (feminine). Most other numbers stay the same regardless of the noun's gender, which makes this rule easy to isolate and learn as a single, specific exception rather than a pattern running through the whole number system.
Numbers above ten are built by combining smaller number words in a regular, additive way, similar in spirit to how English constructs "twenty-one" or "thirty-five" — once you know the words for the tens and the units, compound numbers are assembled rather than memorized individually.
Like other Latvian words, numbers can be affected by the case system (see Latvian Grammar) depending on their role in a sentence — but for everyday counting and basic sentences, the base forms cover the large majority of situations a beginner will need.
Yes — viens is used with masculine nouns and viena with feminine nouns; this gender agreement is specific to "one" rather than a rule running through most other numbers.
Similarly, yes — they're built additively by combining tens and units words in a regular, predictable pattern once you know the base number words.
They can, since Latvian's case system applies broadly across the language, but the base forms are sufficient for the majority of everyday counting and beginner sentences.
As part of the core vocabulary content, introduced with audio before the more detailed gender-agreement and case-related nuances.
See also: Latvian Vocabulary · Latvian Grammar · Learn Latvian