How do you solve this using properties of congruence?
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7To do minimal work, note that the two are incongruent modulo $2$, and therefore modulo $24$. – André Nicolas Nov 07 '15 at 22:39
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I am curious whether someone posts this as an answer and gets several upvotes :) – Peter Nov 07 '15 at 22:44
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@Peter, why don't you try it? – Gerry Myerson Nov 07 '15 at 23:01
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Could've been a typo, although I suppose we may never find out (OP has de-registered?). – Brian Tung Nov 08 '15 at 00:53
2 Answers
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$18\cdot37^{211}$ is even, and $17+12^{99}$ is odd. Since $a\equiv b\pmod{24}$ implies $a\equiv b\pmod 2$ (since $2$ is a factor of $24$), they are not congruent modulo $24$.
Stolen from the comment section.
Akiva Weinberger
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$37\equiv 13 mod 24$
$\Rightarrow$ $37^2=13^2=169=1$ since $168$ is a multiple of $24$
$\Rightarrow$ $37^{210}=(37^2)^{105}=1$
$\Rightarrow$ $37^{211}=37=13$
$\Rightarrow$ $18.37^{211}=18.13=234=-6$
On the other hand $12^{99}$ will be a multiple of $24$ so thats $0$ in $mod$ $24$
So $17+12^{99}=17 = -7 \neq -6= 18.37^{211}$
Edit : I read the comments but had already started foolishly slogging ahead in $mod$ $24$ so thought what the heck and posted. The comment solution is clearly much cleverer.
Arcane1729
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