ADDITION.
Reckon up the following columns of figures.
(9) 234 472 212 424 315 321 821 102 (10) 121 516 361 684
§ 20. PROOF.—Begin at the top and add the columns downward in the same manner as they were added upward. If the two sums are alike the work is presumed to be right.
11. What is the sum of 231, 114 and 324? Answer 669.
12. Required the sum of 235, 321 and 142. Answer 698.
13. What is the sum of 11, 22, 505 and 461. Answer 999. 14. I sold twelve plows for 104 dollars, two wagons for 214 dollars and one chaise for 121 dollars; what is the amcunt of the whole? Ans. 489. 15. A drover bought of one man 125 sheep, of another -432, of a third 311; how many did he buy? Ans. 868. § 21. When the sum of any column is equal to or exceeds 10 the operation is as follows: 1. I have three lots of wild land; the first contains 246 acres, the second 761 acres, and the third 918 acres. I wish to know how many acres there are in the three lots. Answer 1928 acres.
OPERATION Having arranged the numbers as in Acres. the preceeding examples, we first add 2 46 the units; thus, 8 and 4 are 12, and 6 764 are 18 (units), equal to 1 ten and 8 918 units. We write the 8 units under the column.of units, and carry the 1 Amount 1928 ten to the column of tens and add it to thems thus, 1 added to 1 makes 2, and 6 are 8, and 4 are 12 (ters), equal to 1 hundred and ? tens. We write the two tens under the column of tens, and add the one hundred to the column of hundreds; thus, 1 ad- ded to 9 makes 10, and 7 ars 17, and 2 are 19 (hundreds),
