\[a_{n}\ldots a_{2}a_{1}a_{0} - данное\ число.\]
\[1)\ a_{0} + a_{1} \bullet 10 + a_{2} \bullet 100 + \ldots + a_{n} \bullet 10^{n}.\]
\[2)\ a_{0}^{2} + a_{1}^{2} + a_{2}^{2} + \ldots + a_{n}^{2}.\]
\[3)\ a_{k} - цифры:\]
\[a_{1} < 10;\ a_{2} < 100;\ a_{n} < 10^{n};\]
\[a_{1}^{2} < a_{1} \bullet 10;\text{\ \ }\]
\[a_{2}^{2} < a_{2} \bullet 100;\]
\[a_{n}^{2} < a_{n} \bullet 10^{n}.\]
\[4)\ Остается\ одна\ цифра:\]
\[a_{0} = a_{0}^{2}\]
\[a_{0}^{2} - a_{0} = 0\]
\[a_{0}\left( a_{0} - 1 \right) = 0;\]
\[a_{0} = 0;\text{\ \ \ }a_{0} = 1.\]
\[Ответ:\ \ 0;\ 1.\]