Henderson Hamlin's Lightning Calculator - Containing the Shortest, Simplest #263737

It is better to know everything about something, than something about everything.<br><br>Early ideas are not usually true ideas, but need to be revised and re-revised. Right means straight, and wrong means crooked. And knowing that thought kindles at the fire of thought, we do not hesitate or offer any apology for presenting to the Public some new seed-thoughts, and right methods of operation in business calculations. The practical utility of this book is found in the brevity and conciseness of its rules. Particular attention is invited to the grand improvements in the subjects of computing time, all possible cases in Interest, Squaring and Multiplying Numbers, Dividing and Multiplying Fractions, and an infinite number of methods of Extracting Square and Cube Root.