I once read that Thomas Edison could recite the contents of a page from the Webster’s unabridged dictionary after a brief perusal. I also read that an example of photo-memory was someone being able to count the bricks in a wall after a quick look.

My own experience is the occasional after-image experienced on photos of aircraft projected onto a screen at shutter speeds in the hundredth of a second (aircraft recognition training). The lingering impression would remain for a second or two and I think they were in negative image.

Yours truly,
Jay Sicard

Hi, Jay. From everything I’ve read on the subject, memory, and especially photographic memory, is a huge benefit in mental calculation, pretty much a prerequisite for real achievement. This was particularly true back when lightning calculators were asked conversion questions (for example, the number of seconds in 250 years) where the calculator knew all the conversion factors and therefore most of the work was already done. But this is true generally in all kinds of calculating tasks: knowing powers and primes, knowing logarithms for non-integer roots, knowing all 2×2 digit products, knowing factors and reciprocals of a variety of numbers, knowing a lot of reference dates for calendar calculations, and so forth. Smith’s book “The Great Mental Calculators” (which I absolutely recommend) describes the ubiquitous role of memory among lightning calculators. I think, too, that this kind of knowledge is naturally attained anyway by someone enamored with numbers. I certainly don’t have a photographic memory, but I think I once had some ability of this kind. I remember in 5th grade when a teacher questioned something I said in Geography class, and I told her the sentence, page and location on that page where I had read it in our thick textbook. That created a bit of a stir in the class and with her when she looked it up. I recall that I had an exact mental image of the page. I couldn’t do that today, I don’t think. It would be interesting to hear if your “flash” training gives you the same ability with the page of a book or a table of numbers. Maybe you can try it and let me know if it works. As far as counting things instantly, the physicist Richard Feynman recounted (in his book “Surely You’re Joking, Mr. Feynman”, I believe) how with some practice he learned to instantly count the number of toothpicks dropped on a table based on patterns or such. — Ron

He holds/held the European/British record. The World record is current 67,890 digits, cf. http://pi-world-ranking-list.com/lists/memo/.

Ah, right you are–my mistake. I’ve updated the online essay and I’ll do so for the PDF file as well. Thank you very much for taking the time to correct this! — Ron