On Wednesday, 4 October 2017 15:19:41 UTC-4, Markus Klyver wrote: > Den tisdag 3 oktober 2017 kl. 23:30:02 UTC+2 skrev John Gabriel: > > On Tuesday, 3 October 2017 17:15:59 UTC-4, burs...@gmail.com wrote: > > > Can you make an example, where two series cannot > > > be multiplied formally, independent of their > > > convergence? > > > > Birdbrains. It makes no sense to multiply any two series unless they both converge. The idea is that you are multiplying the LIMITs by multiplying the partial sums. > > > > YOU BIG MOOOOOOROOOOOOON!!!! > > You can, but it's no guarantee the product will converge or to what it will converge to. You can multiply two divergent series and get an convergent one, for example.