In excel I would use the formula:
IF(A2=A1, C1+1,1)
What this allows me to do is say, if the value in column A on this row matches the value above it, then increment the value in this cell, if not start again at 1.
When you create a formula like this in excel you can fill it down and therefore have every row reference the row above.
Is there anyway to achieve that in smartsheet?