#### Problem 81E

81. What is wrong with the following calculation?

\begin{aligned}0 &=0+0+0+\cdots \\&=(1-1)+(1-1)+(1-1)+\cdots \\&=1-1+1-1+1-1+\cdots \\&=1+(-1+1)+(-1+1)+(-1+1)+\cdots \\&=1+0+0+0+\cdots=1\end{aligned}

(Guido Ubaldus thought that this proved the existence of God because „something has been created out of nothing.”)