1. The problem statement, all variables and given/known data It is not a homework problem.I just want to clarify whether during the comparison tests of infinite series,should we start the series from n=0 whenever possible? 2. Relevant equations 3. The attempt at a solution Actually,there are many series for which n=0 term is not defined and hence,it is not taken into account.But I saw for (1/2^n) geometric series,it is quite helpful to consider the zeroth term and hence to prove the convergence of (1/n^2) by appropriate grouping method. So,we can use n=0 term of a series even when comparing it with a series starting with n=1 term.Right?