>>>>> On Sat, 01 Feb 2025, Michael Heerdegen wrote:

> One simple possibility could be to predefine ln(10) as a math constant
> and refer to it in the unit definition.  I think we did something
> similar in other places, don't recall the reasons.

This isn't even necessary. calc-math.el already defines math-ln-10, so
we could simply use it.

Something like the attached patch might work. However, I've done only
the most rudimentary testing for it.