'Fifteen' in the Bible

You and your sons and your servants shall cultivate the land for him, and you shall bring in the produce so that your master’s grandson may have food; nevertheless Mephibosheth your master’s grandson shall eat at my table regularly.” Now Ziba had fifteen sons and twenty servants.

There were a thousand men of Benjamin with him, with Ziba the servant of the house of Saul, and his fifteen sons and his twenty servants with him; and they rushed to the Jordan before the king.