I wanted - I really, really wanted - to like this book. On the surface, it's exactly my cup of tea: a whole book of tricks to make mental arithmetic easy. Sadly, there's so much about it that's dreadful that the nuggets inside it are hardly worth the effort.
The binding? Dreadful1. The printing? Dreadful. The layout? Dreadful. The explanations? Negligently dreadful. The content? Occasionally intriguing, but often dreadful. The cover? Dreadful. Not all sayings, it turns out, are correct.
Purportedly based on messages in ancient spiritual writings, Vedic Maths touts itself as a comprehensive system for all of maths. That... it may be. But this book doesn't show it. This book shows a collection of tricks - some of them rather neat, especially the ones for working out the decimal expansion of fractions, and for quickly multiplying numbers near a power of ten - but so many of the others (especially the algebra ones) are based on special cases and/or so poorly explained as to be impenetrable.
It's not clear that this book is intended for an audience outside of colonial India: it talks at great lengths about working in rupees and annas, which were decimalised away in the late 1950s. There are an awful lot of 'hereunder's and 'thereofs' and claims that the system is perfectly clear, much like a politician telling you you can trust him, or a parent saying 'isn't this fun?'. And there are an awful lot of jargon terms for the various methods2 which - to someone who doesn't have a background in the languages of India, leads to a lot of head-scratching and skipping around.
I bought this book some years ago (five? ten? who knows?), and in re-reading it, notice that it's covered in notes desperately trying to make sense of what's going on. Question marks. Arrows with $\times 2$ next to them. A vinculum here, a tear-stain there.
I will gladly hold my hands up and concede that my writing - especially when it's not had the benefit of a For Dummies editor going through and telling me to tidy it up - isn't always as clear as it might be. I'm also guilty, especially in writing for beginners, of not explaining why certain tricks work the way they do. There's a continual trade-off between clarity of method and detail of explanation; it's sometimes necessary to sacrifice one for the sake of the other. The authors of Vedic Mathematics too often do both.
I wish I could recommend this book, but unless you've got weeks to decipher the bits of it that are good, I'd have to recommend buying something else.