The Negative Digital Root Implemented as a Mathematica Standalone Function

This is a new standalone function developed using Mathematica, which is capable of compute the Negative Digital Root of any negative integer. This standalone function is suitable for its inmediate use in any Wolfram Language Computation.

◼ Usage:

NegativeDigitalRoot[n] gives the Negative Digital Root for the negative integer n.

◼ Details & Options:

Consider a negative integer n,
when n < 0 the negative digital root of n is:
* NegativeDigitalRoot[n] = n - (-9) * Floor[(n+1) / -9],

As an example, consider n = -476:
* NegativeDigitalRoot[-476] = (-476) - (-9) * Floor[(-476 + 1) / -9] = -8.
* NegativeDigitalRoot[-476] returns -8.

For any negative integer n:
* 0 > NegativeDigitalRoot[n] >= - 9.

-> Note 1: Standalone function developed on Mathematica 14.0+.
-> Note 2: More mathematical and coding details, graphics and technical information can be found in the notebook (.nb), package (.wl) & pdf files provided in this data pack.