If one or more numbers thought of be greater than 9, we must distinguish0
admin posted in new games on September 25th, 2008
two cases; that in which the number or the numbers thought of is odd,
and that in which it is even
If one or more numbers thought of be greater than 9, we must distinguish
two cases; that in which the number or the numbers thought of is odd,
and that in which it is even. In the first case, ask the sum of the
first and second; of the second and third; the third and fourth; and
so on to the last; and then the sum of the first and the last. Having
written down all these sums in order, add together all those, the
places of which are odd, as the first, the third, the fifth, etc.;
make another sum of all those, the places of which are even, as the
second, the fourth, the sixth, etc.; subtract this sum from the former,
and the remainder will be the double of the first number. Let us
suppose, for example, that the five following numbers are thought of:
3, 7, 13, 17, 20, which, when added two and two as above, give 10, 20,
30, 37, 23; the sum of the first, third, and fifth is 63, and that of
the second and fourth is 57; if 57 be subtracted from 63, the remainder
6, will be the double of the first number, 3. Now, if 3 be taken from
10, the first of the sums, the remainder 7, will be the second number;
and by proceeding in this manner, we may find all the rest.
