# A number theory problem by Wildan Bagus W. Hafidz

$\left( \begin{matrix} 2017 \\ 0 \end{matrix} \right) +\left( \begin{matrix} 2017 \\ 1 \end{matrix} \right) +\left( \begin{matrix} 2017 \\ 2 \end{matrix} \right) +...+\left( \begin{matrix} 2017 \\ 2016 \end{matrix} \right) +\left( \begin{matrix} 2017 \\ 2017 \end{matrix} \right)$

Find the units digit of the number above.

Notations:

• $$\displaystyle {M \choose N} = \frac {M!}{N!(M-N)!}$$ denotes the binomial coefficient.
• $$!$$ denotes the factorial notation; for example: $$8! = 1\times 2 \times 3 \times \cdots \times 8$$.
×