I'm working on the following problem: The drawing shows four point charges. The value of q is 2.0 µC, and the distance d is 0.74 m. Find the total potential at the location P. Assume that the potential of a point charge is zero at infinity. http://www.boomspeed.com/boogiel80/physics19.3.gif [Broken] I converted my charge to 2.0e-6. I used the formula V= kq / r and came up with values of -2.43e4 for each of the parallel charges and the same numbers, only positive, for each of the perpendicular charges. I assumed I was suppose to add all the charges and I got a total of 0 V. However, webassign is saying that is the incorrect answer. Any input would be nice.