[ghkbrew]

I assume they use N⋅D rather than ND to make it explicit these are 2 different variables. That's not necessary for 6N because variable names don't start with a number by convention.

[Quarrelsome]

Its good we all learned this convention. Thanks for teaching to it to me though.

To clarify, if it read:

C ~ X N⋅D

you'd be as confused as me? Its because its a number it has special implied mechanics where we can skip operators because its "obvious".

[ghkbrew]

Well no actually it'd still clear to me that they mean the the multiplication of 3 different variables X, N, and D.

I don't think of it as eliding obvious operators. Rather in mathematics juxtaposition is used as an operator to represent multiplication. You would never elide an addition operator.

So X next to D still means multiplication as long as you can tell that X and D are separate entities.

I would wonder why they switched conventions in the middle of an expression though.