- El proceso anterior, escrito con los signos de (23) es el siguiente:
1834 = 1 × 1000 + 8 × 100 + 3 × 10 + 4
2799 = 2 × 1000 + 7 × 100 + 9 × 10 + 9
Por lo tanto,
1834 + 2799 = 3 × 1000 + 15 × 100 + 12 × 10 + 13
Pero
| 13 = | 1 × 10 + 3 | ||
|---|---|---|---|
| 12 × 10 = | 1 × 100 + | 2 × 10 | |
| 15 × 100 = | 1 × 1000 + | 5 × 100 | |
| 3 × 1000 = | 3 × 1000 | Por lo tanto, | |
| 4633 | 4 × 1000 + | 6 × 100 + | 3 × 10 + 3 |
| = | 4633. |
- The same process is to be followed in all cases, but not at the same length. In order to be able to go through it, you must know how to add together the simple numbers. This can only be done by memory; and to help the memory you should make the following table three or four times for yourself:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
| 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 |
| 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
El uso de esta tabla es el siguiente:
- Supóngase que desea hallar la suma de 8 y 7.
- Busque en la columna de la izquierda cualquiera de ellos, por ejemplo, el 8; y busque en la columna superior el 7.
- En la misma línea que el 8, y debajo del 7, encontrará el 15, que es su suma.
- When this table has been thoroughly committed to memory, so that you can tell at once the sum of any two numbers, neither of which exceeds 9, you should exercise yourself in adding and subtracting two numbers, one of which is greater than 9 and the other less. You should write down a