How to become a Lightning Calculator by Anonymous is part of the HackerNoon Books Series. You can jump to any chapter in this book here. How to Add Two Columns at Once.
How to Add Two Columns at Once.
To the inexperienced it will be a difficult task to add two columns at once, but many of those who have daily practice in addition find it about as easy to add two columns as one. Say 99 and 50 are 149, and 6 are 155, and 10 and 50 are 215 and 3 are 218, and 12 are 230. Carry 2, and say 33 and 12 are 45, and 20 are 65, and 6 are 71, and 30 are 101, and 2 are 103, and 23 are 126.
Much of the information here contained is compiled from W. D. Rowland’s valuable little volume, entitled “How to become expert with figures.” You can get this handy book by sending 25 cents in stamps to American Nation Co., Boston.
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This book is part of the public domain. Anonymous (2021). How to become a lightning calculator. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/65078/pg65078-images.html
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