Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dŭcenti, ae, a (sing. ducentum, Lucil. ap. Non. 493 fin.; Col. 5, 3, 7; gen. ducentūm, Liv. 32, 37 al.; Varr. R. R. 3, 2, 15: ducentarum, Nep. Them. 2, 5: -torum, Front. Aq. 7), num. [duo-centum], two hundred.