'Thirteen' in the Bible

You must offer a burnt offering, an offering made by fire as a pleasing aroma to the Lord: thirteen young bulls, two rams, and fourteen lambs each one year old, all of them without blemish.

Their grain offering must be of finely ground flour mixed with olive oil, three-tenths of an ephah for each of the thirteen bulls, two-tenths of an ephah for each of the two rams,