**Sums are diagonal **or have a diagonal visual effect, when visualised in “Functional Matrices”:

The Diagonals are ODD when ODD Digits are added to EVEN.

But the Geometry of Diagonals is more important than the Arithmetic of Odd or Even!

When ANY sum can be visualised as a Diagonal, so can Prime Numbers of course:

MORE: “Diagonal Sums” and Collection 6: “Diagonal Sums of Odd and Even Summands”