Ordinal Numbers

primus (a, one)

      masc.      fem.       neut.
nom.  primus     prima      primum
acc.  primum     primam     primum
gen.  primi      primæ      primi
dat.  primo      primæ      primo
abl.  primo      prima      primo

Example(s):

    primus uir, prima poma, primum templum. (the first man, a first apple, the first temple.)

These numbers decline according to the first and second declension adjectives (bonus, -a, -um) just as primus has already demonstrated.