The measure 180 for the winter half gives us automatically 360 - 180 = 180 days for the summer too. In G summer begins with period 1 and ends at period 16, i.e. there are 15 periods during summer.

The length of such a summer period must be 12 days, 12 * 15 = 180. The winter season may then (for harmony's sake) be reformulated as:

13 * 14 = 182

12 + 15 = 13 + 14. Furthermore 13 and 14 are inside 12 and 15, suggesting that 13 and 14 are female in character.

365 - 180 - 182 = 3. There are signs that the rongorongo creators may have thought about 3 dark nights at the end of a year. A working hypothesis is that the calendar in G covers a whole year.