The method involving “carrying” is the better one. If equals be added to two numbers, their difference is not changed. In the last example, if 10 is added to 5, to equalize it add 1 to 7, for 10 units of one order equal one unit of the next higher. Adding the 1 to the 7 is called “carrying.”
·· 2 × 1 = 2
:: 2 × 2 = 4
:: : 2 × 3 = 6
:: :: 2 × 4 = 8
&c. &c.
Let the pupils recite the tables orally. Use for drill the following problems:—
987654321
2
_________
123456789
2
_________
With the problem on the board let the pupil recite without the aid of the answer. Similarly use the 3’s, 4’s, 5’s, &c. Along with this part of the work, how to multiply by a number of two or more figures may be taught. Placing the multiplication table in the compact rectangular form found in some arithmetics will be profitable and interesting work.
16. Teach the Roman notation to C; how to tell the time of day; how to make change with money; and how to solve easy exercises in pt., qt., pk., and bu.,—gi., pt., qt., and gal.—and in., ft., and yd.
17. The teacher, using a pointer, should drill the pupils thoroughly on the following table. (Try to acquire speed and correctness).
| 2 × 2 | 3 × 7 | 8 × 5 |
| 3 × 2 | 8 × 3 | 5 × 9 |
| 2 × 4 | 3 × 9 | 6 × 6 |
| 5 × 2 | 4 × 4 | 7 × 6 |
| 2 × 6 | 5 × 4 | 6 × 8 |
| 7 × 2 | 4 × 6 | 9 × 6 |
| 2 × 8 | 7 × 4 | 7 × 7 |
| 9 × 2 | 4 × 8 | 8 × 7 |
| 3 × 3 | 9 × 4 | 7 × 9 |
| 4 × 3 | 5 × 5 | 8 × 8 |
| 3 × 5 | 6 × 5 | 9 × 8 |
| 6 × 3 | 5 × 7 | 9 × 9 |
These constitute the multiplication table with the duplicate combinations cut out, leaving but 36 products to learn in the entire field of the common multiplication table.
18. Let the division tables now be learned.