12. (6 points) The units digit of $3^{2014}+4^{2015}+5^{2016}$ is $\qquad$ . (Note: $a^{m}$ represents $m$ $a$s multiplied together)
【Solution】Solution: According to the analysis, first find the unit digit of $3^{2014}$, $\because 3^{1}=3,3^{2}=9,3^{3}=27,3^{4}=81,3^{5}$ $=243$,

Obviously, the unit digit of $3^{n}$ is $3, 9, 7, 1$ appearing in a cycle of 4, and $3^{2014}=3^{503^{*} 4+2}, \therefore$ the unit digit of $3^{2014}$ is 9;

Then find the unit digit of $4^{2015}$, $\because 4^{1}=4,4^{2}=16,4^{3}=64,4^{4}=256,4^{5}=1024$, obviously the unit digit of $4^{n}$ is $4, 6$ appearing in a cycle of 2, and $4^{2015}=4^{1007 \times 2+1}, \therefore$ the unit digit of $4^{2015}$ is 4; Finally, find the unit digit of $5^{2016}$, $\because 5^{1}=5,5^{2}=25,5^{3}=125,5^{4}=625$, obviously the unit digit of $5^{n}$ is always $5, \therefore$ the unit digit of $5^{2016}$ is 5, the unit digit of $3^{2014}+4^{2015}+5^{2016}$ $=9+4+5=18$, so the unit digit is: 8. Therefore, the answer is: 8.