The 1914 British second edition of Calculus Made Easy is by far the most popular ebook I helped produce for Project Gutenberg: https://www.diffgeom.com/blogs/free-online-math-materials/calculus-made-easy/
Part of my 2010 post for the Distributed Proofreaders blog about the book (full text: https://blog.pgdp.net/2010/10/13/calculus-made-easy/)
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The mathematical study of rates of change and total change, also known as “the differential and integral calculus”, has frightened generations of students. Ironically, this scholastic trauma is often unnecessary: Many formal rules of calculus are nearly trivial to carry out. The mathematical difficulties lie in understanding and using the rigorous logical framework of the calculus—what mathematicians nowadays term “elementary real analysis”—and in establishing the correctness of the formal manipulations and their connections with mathematical interpretations.
Sylvanus Phillips Thompson’s “Calculus Made Easy” gives cogent yet entertaining and irreverent explanations of these easy calculational rules. Justifications are conceptual, but beneficially simplified and intuitive. Popularized and later updated by the recreational mathematics author Martin Gardner, “Calculus Made Easy” has remained a widely-read introductory text for the past century.
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If you’ve had unpleasant experiences with calculus, if your knowledge has grown rusty, or if you’ve simply never encountered this powerful and intriguing branch of mathematics, Thompson’s gem of a textbook should prove a pleasant, thought-provoking, and ultimately rewarding read.
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#Math #Mathematics #ProjectGutenberg
is 99.9% indoors but is having a few minutes of grass time 
