Just like those annoying guys who go to magic shows just work out how the tricks work I've been thinking about the 'tricks' presented above. I've worked out what's wrong with the first one-> infinity has the interesting property that multiplying it by any strictly positive real number leaves it unchanged (i.e. 2 *I = I= 23.6 *I), so some ofthe steps shown above don't work. What is annoying me at the moment is that I can't remember the correct way to sum a series likethe 1-1+1... example (or if this is this defined).