'Twenty' in the Bible

On the twenty and fourth day of the eleventh month, (it is the month of Sebat,) in the second year of Darius, hath a word of Jehovah been unto Zechariah, son of Berechiah, son of Iddo, the prophet, saying:

And he saith unto me, 'What art thou seeing?' And I say, 'I am seeing a flying roll, its length twenty by the cubit, and its breadth ten by the cubit.'