Explanation/Reference:
Using the formula we make the following calculation (see note below for details):
((200000 x 2) x 250)+ (10 x 1024 x (600000 + (2 x 200000))) which calculates to 103400000000 bytes, which is 103.4 GB.
We would need 110 GB.
Note: Formula to estimate content database storage
Use the following formula to estimate the size of your content databases:

Database size = ((D × V) × S) + (10 KB × (L + (V × D)))
Calculate the expected number of documents. This value is known as D in the formula.

Estimate the average size of the documents that you'll be storing. This value is known as S in the

formula.
Estimate the number of list items in the environment. This value is known as L in the formula.

List items are more difficult to estimate than documents. We generally use an estimate of three times

the number of documents (D), but this will vary based on how you expect to use your sites.
Determine the approximate number of versions. Estimate the average number of versions any

document in a library will have. This value will usually be much lower than the maximum allowed number of versions. This value is known as V in the formula.
Reference: Storage and SQL Server capacity planning and configuration (SharePoint Server 2013)
https://technet.microsoft.com/en-us/library/cc298801.aspx