Running total of how many DPs you've used while deciding current level's skill allocation

This, in addition to a separate column in the skills sheet (see other idea), would make skill allocation a snap and less of a headache - trying to keep a mental note of how many you've spent as well as where you've already put them especially when you've realised you've run out and need to take away a few you've used in the second rank that level to the skill!