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$n+S(n)=2104\Rightarrow n<2014 \Rightarrow $n có 4 chữ số Đặt$n=\overline{abcd},(a\neq0)$Do$n<2014 \Rightarrow a\leq2$TH2:$a=2$,ta có:$\overline{2bcd}+2+b+c+d=2014 \Rightarrow \overline{bcd}+b+c+d=12 $$\Rightarrow b=0;c=1;d=0,5(loại)$TH1:$a=1$,ta có:$\overline{1bcd}+1+b+c+d=2014\Rightarrow \overline{bcd}+b+c+d=1013$Do $b+c+d\leq27 \Rightarrow \overline{bcd}\geq 986 \Rightarrow b=9$$ \Rightarrow \overline{9cd}+9+c+d=1013\Rightarrow \overline{cd}+c+d=104\Rightarrow \overline{cd}\geq86$$\Rightarrow$c=8 hoặc c=9*)$c=8\Rightarrow d=8$*)$c=9\Rightarrow d=2,5(loại)$vậy $n=1988$

$n+S(n)=2014\Rightarrow n<2014 \Rightarrow $n có 4 chữ số Đặt$n=\overline{abcd},(a\neq0)$Do$n<2014 \Rightarrow a\leq2$TH2:$a=2$,ta có:$\overline{2bcd}+2+b+c+d=2014 \Rightarrow \overline{bcd}+b+c+d=12 $$\Rightarrow b=0;c=1;d=0,5(loại)$TH1:$a=1$,ta có:$\overline{1bcd}+1+b+c+d=2014\Rightarrow \overline{bcd}+b+c+d=1013$Do $b+c+d\leq27 \Rightarrow \overline{bcd}\geq 986 \Rightarrow b=9$$ \Rightarrow \overline{9cd}+9+c+d=1013\Rightarrow \overline{cd}+c+d=104\Rightarrow \overline{cd}\geq86$$\Rightarrow$c=8 hoặc c=9*)$c=8\Rightarrow d=8$*)$c=9\Rightarrow d=2,5(loại)$vậy $n=1988$