I'm also aphantasia and never considered that people would do blackboard math visibly in their head. I, like you, use verbal memory to store numbers. But I've n

I'm also aphantasia and never considered that people would do blackboard math visibly in their head. I, like you, use verbal memory to store numbers. But I've never been particularly good at doing math in my head. At the same time, I can map 47*68 into a rectangle and either add and subtract slivers to get the right answer, all without seeing it. Something else which blew my mind, people who use image search preferentially to everything. Ironically the only time I use image search (unless I'm trying to find an image) is when I want a graph or tabular data.