(Old) Question posted by Felipe Maia to math.stackexchange.com :
The integer 17 belongs to the residue class modulo m of 24. Find m.
(…) I thought of calculating m for the values of the divisors of 24, that is, making m belonging to D (24). (…)
Definition of residue. The number
in the congruence
is called the residue of
. In the case at hand
and
.
This means that for some integer
the following equality holds
. You should then have
, where
are positive integers. This implies that
, because
is a prime number, that is, it has no divisors, except
and
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