178			58
Gb1-18 (248)	Gb1-19		Gb7-17 (428)	Gb7-18		Ga1-16 (488)
	180 = 2 * 90			60

Twice 248 = 496 (= 16 * 31), and then comes Ga1-25:

Ga1-15	Ga1-16 (488)	Ga1-17	Ga1-18
Ga1-19	Ga1-20	Ga1-21
Ga1-22	Ga1-23	Ga1-24 (496)	Ga1-25

Ga1-25 occupies, we have seen, a crucial place in the structue of the text, as illustrated for instance in this table:

	258						208
Gb1-6		Ga1-22	Ga1-23	Ga1-24	Ga1-25	Ga1-26
	261 = 9 * 29
472 = 16 * 29 + 8 (= 16 * 29.5)

By measuring to 16 * 31 (counted from Gb8-30) a new cycle will begin with Ga1-25. The new cycle maybe is meant to cover 16 * 28 = 448 days, because 472 - 24 = 448.