'Thirty' in the Bible

So the Philistines fought. Israel was defeated; they all ran home. The slaughter was very great; thirty thousand foot soldiers fell in battle.

Then Samuel brought Saul and his servant into the room and gave them a place at the head of those who had been invited. There were about thirty people present.

Saul was [thirty] years old when he began to reign; he ruled over Israel for [forty] years.