Don't stress out about G.P.'s ppl,
after all, the greatest French mathematician (and generally the greatest intuitionist) of all time Henri Poincare did not even know how to prove the formula for the sum of a G.P. during a matriculation exam!
(of course, he was under pressure from being late to the exam and all, but still... )
so you may all discover the hidden mathematical genii within you yet!
P.S. True story.