Imber Ranae dixit:No, you must keep unus singular, but it declines according to gender and case. So it would be viginti unus canes if nominative and viginti unum canes if accusative. (Unless they're all bitches, in which case you'd use the feminine forms una and unam, respectively.)
Thank you, you taught me so much . Btw guys do you know a site where I can learn good latin vocabulary? I know that I can find many words in my book, but I want to know wich are the most common and most important to know.Adler dixit:The plural ūnī, ūnae, ūnă, can only be used, a) when joined with substantives that are pluralĭa tantum, i. e. used in the plural only; as ūnae scōpae, one broom; ūnae litterae, one letter; ūnă castra, one camp; in ūnīs aedibus, in one house; b) when it assumes the sense of "only," "alone," "one and the same," "like," &c.; as tres uni passus, only three steps; unis moribus, with one and the same kind of manners, &c.