Addition.
Addition.—Operation which consists in taking in any order all the units and portions of units of several numbers and forming with them a single number called their Sum or Total.
Addition of Long Columns of Numbers.—When long columns of numbers are to be added, the student should endeavor to add more than one figure at a time. He may pick those which aggregate 10, 15, 20, etc., and add the intermediate figures when convenient.
Sign of Addition.—The sign of addition is the horizontal-vertical or Roman cross + placed between all the numbers to be added; it is read Plus.
To Prove an Addition.—The shortest way to prove an addition is to do it over again from bottom to top.
Sign of Equality.—The sign of equality is two short equal horizontal parallels =; it reads Equal.