Addition is that operation by which we find the amount of two or more numbers. The method of doing this in simple cases is obvious, as soon as the meaning of number is known, and admits of no illus tration. A young learner will begin at one of the numbers, and reckon up as many units separately as there are in the other, and practice will enable him to do it at once. It is impossible, strictly speak ing, to add more than two numbers at a time. We must first find the sum of the first and second, then we add the third to that number, and-so on. However, as the several sums obtained are easily re tained in the memory, it is neither neces sary nor usual to mark them down. When the numbers consist of more figures than one, we add the units together, the tens together, and so on. But if the sum of the units exceed ten, or contain ten several times, we add the number of tens it contains to the next column, and only set down the number of units that are over. In like manner we carry the tens of every column to the next higher. And the reason of this is obvious from the va lue of the places ; since an unit in any higher places signifies the same thing as ten in the place immediately lower.
Rule. Write the numbers distinctly, units under units, tens under tens, and so on. Then reckon the amount of the right hand column ; if it be under ten, mark it down : if it exceed ten, mark the units only, and carry the tens to the next place. In like manner carry the tens of each co lumn to the next, and mark down the full sum of the left-hand column.
Ex. 1. Ex. 2. Ex. 3.
432 10467530 457974683217 215 37604 2919792935 394 63254942 47374859621 260 43219 24354642 409 856757 925572199991 245 2941275 473214 132 459 499299447325 694 41210864 317 52321975 41 492 4686 5498936009 242 43264353 943948999274 — -- Ans,3833 As it is of great consequence in busi ness to perform addition readily and ex actly, the learner ought to practise it till it become quite familiar. if the learner
can readily add any two digits, he will soon add a digit to a higher number with equal ease. It is only to add the unit place of that number to the digit, and if it exceed ten, it raises the amount accord ingly. Thus, because 8 and 6 are 14, 48 and 6 are 54. It will be proper to mark down under the sums of each column, in a small hand, the figure that is carried to the next column. This prevents the trou ble of going over the whole operation again, in case of interruption or mistake. If you want to keep the account clean, mark down the sum and figure you carry on a separate paper, and after revising them, transcribe the sum only. After some practice, we ought to acquire the habit of adding two or more figures at one glance. This is particularly useful when two figures which amount to 10, as 6 and 4, or 7 and 3, stand together in the column. Every operation in arithmetic ought to be revised, to prevent mistakes; and as one is apt to fall into the same mistake if he revise it in the same man ner he performed it, it is proper either to alter the order, or else to trace back the steps by which the operation advanced, which will lead us at last to the number we began with. When the given number consists of articles of different value, as pounds, shillings, and pence, or the like, which are called different denominations, the operations in arithmetic must be re gulated by the value of the articles. We shall give here a few of the most useful tables for the learner's information, re ferring for other information to the arti Cies, MEASURES, WEIGHTS, &C.