'Twentieth' in the Bible

The words of Nehemiah the son of Hacaliah. Now it happened in the month Chislev, in the twentieth year, as I was in Shushan the palace,

It happened in the month Nisan, in the twentieth year of Artaxerxes the king, when wine was before him, that I took up the wine, and gave it to the king. Now I had not been [before] sad in his presence.

Moreover from the time that I was appointed to be their governor in the land of Judah, from the twentieth year even to the two and thirtieth year of Artaxerxes the king, [that is], twelve years, I and my brothers have not eaten the bread of the governor.