How to become a lightning calculator

CONTENTS
Multum in Parvo Library.
Vol. I.
February, 1894. Published Monthly.
No. 2.
Smallest Magazine in the World. Subscription price, 50 cts. per year. Single copies, 5 cents each.
PUBLISHED BY A. B. COURTNEY, 671 Tremont Street, Boston.
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Accuracy should be first considered, then rapidity. Quick adders, by the way, are the most accurate. Write the numbers in vertical lines, avoiding irregularity. This is important. Keep your thought on results not numbers themselves. Do not reckon 7 and 4 are 11 and 8 are 19, but say 7, 11, 19 and so on.
When the same number is repeated several times, multiply instead of adding.
When adding horizontally begin at the left.
In adding long columns, prove the work, by adding each column separately in the opposite direction, before adding the next column. Many accountants put down both figures as in the illustration. The sum of the first column is 12; carrying one , the sum of the second is 20; carrying two , the sum of the third column is 15; carrying one , the sum of the fourth column is 21, and the total, 21502, is found by calling off the last two figures and the right-hand figures, following the wave line in the illustration. This method is better than the old one of penciling down the number to carry . If one desires to go back and add a certain column a second time, the number to carry is at hand and the former total is known.