Why 16

[Lord Bookwyrm Spren]

Is there a reason behind why Adonalsium was split into 16 Shards? (other than there being 16 people - technically 17, but Hoid doesn't count since he didn't take a Shard). Also, does every Shard have a specific number? e.g. Odium = 9, Honor = 10, Preservation = 16

Edited December 3, 2017 by Lord Bookworm

[King Cole Forger]

Yes, every Shard does have a specific number 

Quote

Questioner [PENDING REVIEW]

I have a theory that each one of the Shards is related to a certain number. Preservation really likes 16, Honor likes 10, and Odium likes 9. Am I onto something?

Brandon Sanderson [PENDING REVIEW]

Yes.

https://wob.coppermind.net/events/175-oathbringer-houston-signing/#e8381

[Ammanas Rambleman]

I dont particularly believe in numerology, but do find it fascinating. Here is what they say about 16:

Karmic Debt number 16

The 16 Karmic Debt represents destruction of the old and birth of the new. The 16 is about the fall of the ego and all that it has built for itself; it is a cleansing. All that has been constructed and all that serves to separate the person from the source of life is destroyed. Through the 16, reunion with the great spirit is accomplished.

This can be a painful process, because it usually comes after much ego inflation. Life presents challenges to your grand plans and you tend to make choices that seem specifically designed to break down what you have previously built -- a self-destructive career choice or an act of stupidity that ruins an otherwise wonderful relationship, for example.

The 16 Karmic Debt is a lost battle and you will likely feel humbled in the face of the collapse that follows. But this humility is the key to later success, because you will learn to follow the intimations of a higher reality, approaching life with an entirely new awareness. It is a life much the better for the fall.

Those with the 16 Karmic Debt must be careful of egoism. Very often, those with the 16 use their highly intuitive and refined intellect to look down upon others, and view the rest of the world as inferior, leading to acute alienation and loneliness.

When the 16 is in one of the Core numbers, this process of destruction and rebirth is a continuous cycle that actually serves to bring you into higher consciousness. The 16 Karmic Debt can be a path of progress and great spiritual growth if it is looked at properly.

https://www.numerology.com/numerology-news/karmic-debt-numbers

[DJScrub Skaa]

Brandon has answered this, at least from a behind the sausage perspective:

https://wob.coppermind.net/events/256-oathbringer-london-signing/#e8655

Obviously this doesn't include any in-universe explanation he came up with to justify it.

Edited December 3, 2017 by DJScrub