Đáp án+Giải thích các bước giải:
Đề thiếu
$\overline{abc}=11k+5\\\overline{deg}=11n+5$$\\$`Ta có:\overline{abcdeg}=1000\overline{abc}+\overline{deg}`$\\$`\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =1000.(11k+5)+(11n+5)`$\\$`\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =11000k+5000+11n+5`$\\$`\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =11000k+5005+11n`$\\Vì ,11000k \vdots 11\\5005\vdots 11\\11n\vdots 11\\$`=>\overline{abcdeg} \vdots 11`