[hackandthink]

(when following Wald's work on rearranging series)

This is a nice riddle:

Is summing the series:

1, -1, 1, 1,....

0 = (1-1)+(1-1)+(1-1)....=0+0+0...

or

1 = 1+(-1+1)+(-1+1)+(-1+1)....=1+0+0+0...