'Thirty' in the Bible

So the Philistines went to the fight, and Israel was overcome, and every man went in flight to his tent: and great was the destruction, for thirty thousand footmen of Israel were put to the sword.

Then Samuel took Saul and his servant into the guest room, and made them take the chief place among all the guests who were there, about thirty persons.

And he had them numbered in Bezek: the children of Israel were three hundred thousand, and the men of Judah thirty thousand.