To be honest, all the research and investigation into this is almost irrelevant... Theres no accurate way to figure the total number out... Even if they counted every single corpse they found or dug up 54 years ago, the number would still be far off the mark...
500lb bombs dont just kill with fragments, they also dismember....
The number of refugees, POW's, slave labor hands, civilians and German troops that were in and around Dresden is a wild guess, so figuring a proportion of those killed is a mathmatical equation with no solution....