Mathemagician Video

[Valentin Albillo]

(07-19-2021 08:24 PM)Jim Horn Wrote:  Mental arithmetic - it's fun![...] As someone who celebrated his 25000th day last Friday, I admire those with that skill and try to improve my own.

I've been also very fond of mental math since I was a teen, and with the passing years I learned a number of easy techniques to help performing a lot of reasonably complex calculations in my head, achieving at least slide-rule precision results (3 significant digits). This would include such things as computing 2^100 or factorials of large/non-integer arguments, things like that. I still can do it, of course.

But another quite interesting topic on mental math I've never seen discussed anywhere is the computations you can do while dreaming !

In my experience, I've been able to multiply a 4-digit number by a 3-digit number and achieve the correct result while in a dream, so though in the dream I used paper and pencil, it was obviously done in my sleeping mind. Most interestingly, a few months ago I was able to invert a 3x3 matrix with one-digit integer elements while dreaming, which is my best dreaming-math achievement so far.

In my experience, one difficulty of doing math while dreaming is that numbers and texts tend to change from glance to glance, as do the covers of books, street signs, underground station names (so you usually get lost when trying to go somewhere) and the like, but if you manage to stay focused you'll successfully complete the operation sometimes.

Another difficulty is that though I can do some math while dreaming, it takes a lot of effort and the operation proceeds very slowly. This amazes me in the dream, because I notice the unexpected effort and the slowness and I can't fathom why is that, since I know I can do these operations at much higher speeds with little effort. It would be a telltale that indeed I'm dreaming but usually I don't take the hint !

Perhaps I could use that as my totem (as per Inception): if I try to multiply two 3-digit numbers using pencil and paper and it takes me a lot of effort, then I'm dreaming.

Best regards.
V.