Taylor,
Thank you for your astute question.
What if we *could* use a numeric passage even with this multiplication problem with letters? We think you could by using grade 1 symbol indicators and a firmly worded transcriber’s note. Please see attached for a possible transcription.
The transcriber’s note used in our example is, “In the problem below, a grade 1 symbol indicator .=; only affects the symbol immediately after it.” Another possible wording might be, “In the problem below, only a symbol that comes immediately after a grade 1 symbol indicator .=; is a letter.”