'Fifties' in the Bible

It had happened that when Jezebel killed the prophets of Yahweh, Obadiah took a hundred prophets and hid them {by fifties} in the cave and sustained them [with] food and water.)

Has it not been told to my lord what I did when Jezebel killed the prophets of Yahweh? I hid a hundred men of the prophets of Yahweh {by fifties} in the cave, and I sustained them [with] food and water.