**In analogy** **to **“HexaDecimal” [6 & 10], the most accurate descriptor of applying ‘digital logic’ to the decimal number system would be “DigitoDecimal” [digit & 10].

However, I am aware of the complexity and novelty of concepts I am introducing with new terms. So let’s stick to “Digital Sums” to describe the sums of a *decimal *product and a *decimal* digit.

The arithmetic of *“Digital Composition” *has lead to interesting VISUAL patterns of prime numbers:

- outside [parallel to the outer digonals]

and inside the “Pyramid of Decimal Counting”:

and

- as “Digital Sums” on “parallel diagonals” in orthodiagonal Number Planes:
- Collection 15. The OrthoDiagonal Nature of “Digital Sums”.

But VISUAL patterns are the result of NUMERICAL repetitions or similarities.

NUMERICALLY, “Digital Sums” reveal steps of:

- ±10
*vertically* - ±1
*horizontally* - ±11
*diagonally* - and a remarkable preponderance of Prime Numbers:

NEXT: “2. Digital RATIOS”