Yes, the article is great (now I've read it). 37*3 also ends in 3 but is not divisible by 3. Thus, were the range not capped at 30 it may have been illegitimat

Yes, the article is great (now I've read it). 37*3 also ends in 3 but is not divisible by 3. Thus, were the range not capped at 30 it may have been illegitimately discarded by the criteria. I think the 3 combined with the 5 digits and 20-30 range, made my guess a bit lucky. It's also contrived for that cube, so not useful for others, other than perhaps as a direction to go in (and likely arrive at the article).