Question

AFLATI NUMERELE DE FORMA 13Y9X DIVIZOR 18

Answer 1

$18\mid\bar{13y9x}\Rightarrow$

$2\mid\bar{13y9x}~si$
$9\mid\bar{13y9x}$

Din prima avem
$x\in\{0,2,4,6,8\}$

Din a doua avem
$1+3+y+9+x~\vdots~9$
$4+x+y+9~\vdots~9$
$4+x+y~\vdots~9$

$x=0\Rightarrow4+y~\vdots~9\Rightarrow y=5$
$x=2\Rightarrow6+y~\vdots~9\Rightarrow y=3$
$x=4\Rightarrow8+y~\vdots~9\Rightarrow y=1$
$x=6\Rightarrow10+y~\vdots~9\Rightarrow y=8$
$x=8\Rightarrow12+y~\vdots~9\Rightarrow y=6$
$\bar{13y9x}\in\{13590,13392,13194,13896,13698\}$