I read this book about 5 years ago, and I didn't understand much then.
But I just read it again, and it's incredible how I now understand
everything.

The book also got me to come up with my own methods.

It would be interesting to know, if the methods in the book,
printed in 1966, are still valid or if there are nowadays
newer methods?

I'm not familiar with Lorayne's book but from reading the blurb it sounds like it's a speed arithmetic programme. Again, without having read the book I cannot answer directly your question regarding the relevance, however there are two other classical systems which are worth you taking a look at: the Vedic system, and the Trachtenberg system.

Interestingly all three books (The Trachtenberg Speed System of Basic Mathematics (1960), Vedic Mathematics (1965), and Miracle Mathematics (1966)) were published within a few years of one another. The relationship between the first two book is well documented throughout the internet, with plenty of opinions of which system is better. I'd be interested to know to what extent Lorayne's ideas are aligned with the proceeding two.

In all, these so called `systems' are in essence a collection of tricks which can be employed to simplify mental calculation, and most likely pre-date all three authors: in the case of Vedic mathematics, the author claims to have discovered several ancient Sanskrit texts in the early 19th century which made up the fundamental contents of his book. In light of that I would imagine that any more modern approach will once again be based on ancient ideas, rather than being anything truly revolutionary, but I cannot be sure on that point!

Owen

Interesting!

I tried to check out the Trachtenberg system a few years ago,
but didn't understand much. But since the same happened with
the Lorayne book, I'll look into Trachtenberg again.