Impressive! I recall that I studied Jakow Trachtenberg's book on speed multiplication when I was 11 or 12. I don't recall all the rules; that was over half a century ago.
I lived in a small town in the lower desert of southern California, and the only other entertainment in town was watching fenders rust in the wrecking yard...a slow process, in the desert.
Trachtenberg, via wiki- https://en.wikipedia.org/wiki/Trachtenberg_system
I lived in a small town in the lower desert of southern California, and the only other entertainment in town was watching fenders rust in the wrecking yard...a slow process, in the desert.
Trachtenberg, via wiki- https://en.wikipedia.org/wiki/Trachtenberg_system
If you get to thinking you’re a person of some influence, try ordering somebody else’s dog around.
