COLUMN LOOKUP.

[lorigraf_LORIl60]

So if anyone can help , I want to find the last number in a column. Sometimes the last cell is blank and when that happens I would want that last blank cell to be a zero. Maybe some kind of IFERROR formula? 

[#2]

@lorigraf_LORIl60 

Depends what do you mean under the column, if some range that could be like

=INDEX(A1:A80,AGGREGATE(14,6,1/(ISNUMBER(A1:A80)+ISBLANK(A1:A80))*ROW(A1:A80),1))

[#3]

Another possibility, I think:

=LOOKUP(MAX(A1:A10)+1,--(A1:A10))