I think mentalism/psychic calculators are cool. For the basic add-a-number effect, I even think that they are superior to number pads because, when the pressure is on, a spectator charged with adding a few numbers can panic and screw up the math. In this top-notch e-book, not only do you get excellent instructions with color pictures on how to build one of these babies, but you get a plethora of tricks for psychic, normal, and cell phone app calculators, as well as some neat mathematical concepts.

That's the great news. There is some slightly bad news. The best calculators to modify--that is, el cheapo solar-powered ones with just the right keyboard configuration--are becoming harder to find. I got mine from Amazon. And even then, the construction is such that disassembling the Casio model was much more difficult than expected because they put in a bunch of pop-rivets to hold the circuit board down. I cracked two boards before I figured out what to do. The calculators were cheap, less than $9 each, so it wasn't devastating, just a little more work than expected. I don't want to put anybody off by my experience. If you get the right calculater, there is nothing to the construction. You may have better luck with another of the suggested models.

So there you have it. In about an hour, I had am ingenius electronic marvel to add to my bag. Along with his books on gaffed cards and gaffed pens (excellent too), Shawn is pretty much the man when it comes to telling you how to do a magic DIY project. He writes well and gives you good details and pictures. (C'mon, Shawn, do a treatise on gaffed envelopes or imp devices.) Sure, you can buy a commercially manufactured psychic calculator for more money, but where's the satisfaction in that? If you are a mentalist and want to build a calculator, this book is a no-brainer. Even if you don't build the calculator, the ordinary calculator and cell phone calculator tricks are worth the price.