| Example 3. | Think of a number, say | 9 |
| Multiply by 3 | 27 | |
| Add 2 | 29 | |
| Multiply by 3 | 87 | |
| Add 2 more than the number thought of (11) | 98 |
The number of tens in the last answer gives the number thought of, viz., 9.
| Example 4. | Think of a number, say | 7 |
| Multiply by 3 | 21 | |
| [If product be odd] add 1 | 22 | |
| Halve it | 11 | |
| Multiply by 3 | 33 | |
| [If product be odd] add 1 | 34 | |
| Halve it | 17 |
Ask how many 9’s are in the remainder, when, of course, the reply will be 1.
The secret is to bear in mind whether the first sum be odd or even. If odd first time, retain 1 in the memory; if odd a second time, 2 more, making 3; to which add 4 for every 9 contained in the remainder.
In the above example, there being only one 9 in 17, this gives us 4, which added to 3 produces the number thought of—7. When even simply add 4 for every 9 in remainder.
HOW TO TELL THE AGE OF A PERSON.
Tell a person to write down the figure which represents the day of the week on which he was born;—thus, 1 for Sunday, 2 for Monday, and so on; next, the figure for the month—1 for January, 2 for February, &c.; then the date of the month; now tell him to multiply the number thus formed by 2, add 5, multiply by 50, and then to add his age, and from this sum to subtract 365; now you ask him for the remainder, to which you secretly add 115.