THE RESOLUTION OF
158
PROBLEM IX.
Supposing 87* + 256?/ = 15410; to determine the least
value of x, and the greatest of y, in whole positive
numbers.
By transposition and division, we have
V —
15410—87*
256
_ 87* — 50 . -
CO —— : where the frac-
2?6
tion being the same with that in Ex amp. l. to the pre
mised lemma, the required value of* will he given from
thence z= 30; from thence that of y will likewise be
known. But I shall in this place shew the manner of
deducing these values, independent of all previous con
siderations, by a method on which the demonstration
of the lemma itself depends.
In order to this, it is evident, as the quantity 87* — h
(supposing b — 50) is divisible by 256, that its double
174* — 26 must be likewise divisible by 256. But
256r is plainly divisible by 256; and if from this the
quantity in the preceding line be subtracted, the re
mainder, 82* 4- 2b will be likewise divisible by the
same number; since whatsoever number measures the
whole, and one part of another, must do the like by the re
maining part: for which reason, if the quantity last
found be subtracted from the first,the remainder 5*—3b
will also be divisible by 256: and, if this new remain
der multiplied by 16, be subtracted from the preceding
one (in order to farther diminish the co-efficient of *),
the difference 2* 4 50b must be still divisible by the
same number. In like manner, the double of the last
line, or remainder, being subtracted from the preceding
one, we have *— 1036, a quantity, still, divisible by
256 : but
1036
256
, 30
= 20 xi
256
therefore * — 30 must
be divisible by 256; and consequently * be either equal
to 30, or to 30 increased by some multiple of 256; but
30, being the least value, is that required.
It may not be amiss to add here another Example, to
illustrate the way of proceeding by this last method:
wherein let us suppose the quantity given tobe
987*4051
1235