TO TELL THE NUMBER THOUGHT OF BY A PERSON.
Desire the person who has thought of a number to triple it, and to take the exact half of that; triple that half if the number was even, or if odd multiply the larger half by 3; and ask him how many times that answer contains nine: for the answer will contain the double of that number of nines, and one more if it be odd. Thus if the number thought of is 5, its triple will be 15, which cannot be divided by 2 without a remainder. The greater half of 15 is 8. If we multiply this by 3 we have 24, which contains 9 twice. So we shall have 2 + 2 + 1 = 5, the number first thought of.
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