Daniel says he has a unique synesthetic reaction like that for every number up to 10,000, and that experiencing numbers in this way allows him to do quick mental math without pencil or paper. To multiply two numbers, he sees each number’s shape floating in his mind’s eye. Intuitively, and without effort, he says, a third shape, the answer, forms in the negative space between them. “It’s like a crystallization. It’s like developing a photo,” Daniel told me. “Division is just the reverse of multiplication. I see the number and I pull it apart in my head. It’s like leaves falling from a tree.”
...more
