Fixed running total

Hi
I know how to total sum cells together but-
I need for example, if AA5,AA6,AA7,AA8= 1 (AA5 has 1 in it) and i change the value in AA5 back to 0 the sum total stay fixed at 1, so if AA6 was to show 3 it would =4 and keep an ongoing total regardless of numbers changing back to 0 in above cells, make sense?


Moderator's note: Cross-posted at https://www.mrexcel.com/forum/excel-...ing-total.html