It would come much more naturally to a native speaker to say not "That man is a 50-year-old" [note also the hyphenation here] but "That is a 50-year-old man"; similarly, not "That kid is a one-and-a-half-year-old today" [a construction I have never heard anyone use when referring to half years as part of someone's age], but "That is a one-and-a-half-year-old kid" (omitting the 'today'), or ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.