Decades ago, I was reading about tricks, or as it was put, a systematic approach to do arithmetics without a pen. Those were paid courses.

It should have been obvious by then how irrelevant the whole thing was, since calculators with all kinds of shapes and forms were already widely available.

When you look at this page, there is a fair amount of memorization needed to make it somewhat useful. Then you don't want to make any mistakes in any of the steps. And you want to make sure you still remember everything by the time you need to use it.

That is a very roundabout way to say that I am fairly confident that nobody is actually going to "learn" what's in the page and apply it in realistic situations, and it's a complete waste of electricity to vibe code this page.