Well, you can assign the notations U1, U2, U3, U4... to the nodes and write up all the equations, but you always get one less independent equations than the number of nodes. As an example, you have 4 nodes, and at the end you arrive to the solution U2=U1+6, U3=U1-2, U4=U1+10. You can choose any value for U1, but U1=0 is the simplest. If you fancy, it can be U1=1.4141 :)
ehild