My autistic son started doing this when he was a little over five years old. I thought it was miraculous, until I came across this formula — in fact, it may have been you who posted it elsewhere. You suggested then that this was not such a big deal, as anyone who learned the formula could perform the calculation.
I took this argument at face value until I thought about it a little more deeply with regard to my son’s case.
In the first place, it’s not an overly complex formula for many people, but for many others, it actually is. It’s not rocket science, but it’s not simple arithmetic, either.
In the second place, my son was never taught this formula. Somehow he came up with it on his own. He started asking people for their birthdates—it was about all he would ask anyone—and then he’d tell them the day of the week they were born. I started to go back in time with him to figure out the days of the week historical figures were born, and he was always right.
What’s interesting is he’s mostly lost this ability. He can do it every now and again, but not as accurately and not as often. We were told by one neuropsychologist that many of these “splinter” skills will come and go during his childhood, and we have certainly found that to be the case.
