Rapid Math Without a Calculator

"Rapid Math Without a Calculator", by A.F. Collins, Reprinted Citadel Press, NJ, 1956/1987/2006. (Originally ISBN 0-8065-1058-7). Soft cover, paged, illustrations & tables, & Index. 8 1/4" x 5 3/8". Author, noted mathematician & physicist, introduces basic arithmetic nomenclature, then focuses on methods including rapid addition & subtraction, short cuts in multiplication, division, fractions, finding square & cube roots, and concludes with useful tables & formulas and a brief introduction to magic with figures including magic squares, etc. The short cuts in multiplying & dividing certain number sets by using the complement or sliding methods and use of "casting out nines" or "method of unitates" (sum of figures making up a number reduced to one figure) to verify answers is intriguing. Current dependency on modern pocket-sized calculators can be devastating, for if they malfunction, persons not familiar with performing conventional or short cut arithmetic may be in a quandary, including the average person whether student, businessman, or homeowner. Collins describes techniques to evince rapid end-results using easily learned unconventional formats. Significantly, the book has been reprinted and updated and expanded since its original publication.

Easy tips, that are fast and practical. I only wish I'd found it years ago.