Rings and unity The set $R = {([0]; [2]; [4]; [6]; [8])}$ is a subring of $Z_{10}$. (You do not need to
prove this.) Prove that it has a unity and explain why this is surprising.
Also, prove that it is a field and explain why that is also surprising.
This sis a HW Question.
The unity is not [0] is it ?? Could I get a hint ???

Notice that $[6]\times[a]=[a]$ for $a=0,2,4,6,$ and $8$.  See if you can do the rest!
