Can $R[[x]]$ contain constants? 
Consider the ring $R[[x]]$ of formal power series $\sum_{n=0}^\infty a_nx^n$ with coefficients in $R$. I was wondering whether $R[[x]]$ contains elements of $R$ (polynomials of degree $0$). 

I'm trying to solve Commutative Algebra problems. I feel it is possible, as all of $\{a_1,a_2,\dots\}$ simply have to be equal to $0$, which I think is possible.  
Thank you.

Yes, it can. ${}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}$
