'Twentieth' in the Bible

The words of Nehemiah the son of Hachaliah. And it came to pass in the month Chisleu, in the twentieth year, as I was in Shushan the palace,

And it came to pass in the month Nisan, in the twentieth year of Artaxerxes the king, that wine was before him: and I took up the wine, and gave it unto the king. Now I had not been beforetime 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 unto the two and thirtieth year of Artaxerxes the king, that is, twelve years, I and my brethren have not eaten the bread of the governor.