We end up with 3, 2, 1 or 0 yarrowstalks when divining. About 1200 BC those four numbers were III, II, I and blank space. These numbers doesn't work with hexagrams, but the sages solved the problem by using backwards-moving numbers:

0 was named 8
1 was named 7
2 was named 6 ("Earth", below the horisontal line of the pictograph)
3 was named 5 ("Heaven", above looks like the sun and the moon)

The three Chang inscriptions on the Anyan village Sinpanmo scalpula bone :

http://www.yijing.nl/i_ching/books/bagua.htm

o1 = I:I:I: Yi Jing no. 64.1.3.
o2 = I:I Yi Jing no. 36.3.4.5.
o3 = III Yi Jing no. 12.1.2.3.5.

number 5 = B Light and Yielding = 3 stalks
number 6 = /\ Dark and Firm = 2 stalks
number 7 = + Light and Firm = 1 stalk
number 8 = )( Dark and Yielding = 0 stalks

Exactly the same Chang-number characters are used on these inscriptions:

o9 = :I:I:I Yi Jing no. 63.1.
10 = I::I:: Yi Jing no. 52.1.2.4.5.
12 = II: Yi Jing no. o4.1.3.5.
25 = III Yi Jing no. 42.2.3.4.5.
33 = III Yi Jing no. 41.3.4.

Then the number inscriptions on oracle bones were changed/simplified by the Zhou :

number 5 = + Whole changing line = 3 stalks
number 6 = /\ Broken changing line = 2 stalks
number 7 = - Whole steady line = 1 stalk
number 8 = )( Broken steady line = 0 stalks

o4 = ::II:I Yi Jing no. 55.2.6.
05 = III::I Yi Jing no. 25.3.6.
o6 = II: Yi Jing no. 46.1.5.6.
o7 = I:I Yi Jing no. 27.2.3.4.5.
o8 = II:III Yi Jing no. 9.4
11 = I::II: Yi Jing no. 18.4.5.6.
16 = II::I: Yi Jing no. 59.1.4.
30 = III Yi Jing no. 41.3.
31 = II:I:: Yi Jing no. 53.1.3.4.5.
35 = ::I:I: Yi Jing no. 40.3.4.5.6.

These two are hard to read due to the quality of the chart:

18-19

There are only two examples with both - and +:

32-34 (maybe the diviner forgot the last vertical stroke below in each hexagram?)

The remaining are not six numbers, but might include trigrams?

13-14-15-17-20-21-22-23-24-26-27-28-29-36

Oracle bones were pyromancy divination "books". The "I_II_I" pictographs on the oracle bones means "bamboo book".
The reason why so few hexagrams are written on bones is of course, that they were written in these bamboo books.

http://zhouyi.sdu.edu.cn/english/yiology/sub2/aStudyOfTheLatestDiscovered.asp

lienshan said:

We end up with 3, 2, 1 or 0 yarrowstalks when divining. About 1200 BC those four numbers were III, II, I and blank space. These numbers doesn't work with hexagrams, but the sages solved the problem by using backwards-moving numbers:

0 was named 8
1 was named 7
2 was named 6 ("Earth", below the horisontal line of the pictograph)
3 was named 5 ("Heaven", above looks like the sun and the moon)

Click to expand...

This doesn't compute. The etymology for the number 5 (wu3) is...

View attachment 327

...representing the Five Elements (the "X"... four sides and a center) between Heaven and Earth (the top and bottom lines). Where do you get ("Heaven", above looks like the sun and the moon)? I'm equally puzzled by your statement that 6, below the horizontal line of the pictograph, could represent Earth. Could you explain this, please?

Hi getojack

The number 5 shown looks to me like two light (sun and moon) subjects seperated i the middle and the sign 5 too looks like the sign "Di", the Shang god Heaven. To me the Chang number 6 have the shape of their sign "below" (a short line above a long line).

It's a code. It's impossible to make hexagrams with ordinary Chang 3, 2, 1, 0 numbers, because they are III, II, I lines and blank space. The code is written in Shuo Kua and says, that to Heaven the holy sages assigned the number three (III)
and to Earth they assigned the number two (II).

This explains the main difference between Chang and Zhou hexagrams:

The Chang hexagrams were four numbers (5,6,7,8) equally rated wich produced 4x4x4x4x4x4 = 4096 answers.
The Zhou hexagrams were 64 standards of 7 and 8 (steady lines) with each six changing lines = 384 answers.

No wonder that the Book of Changes version Kuei Ts'ang made of bamboo-slips was named "the elephant"