Hi

Enter first serial number in A2, then insert this formula in A3 and copy
down. If cargo cell is empty, serial number cell will also be empty.

=IF(C3<"",IF(C3<C2,A2+1,A2),"")

Hopes this helps.
....
Per

"clint" skrev i meddelelsen
...
column A titled "serial number", column B titled "line item", column C
titled
"cargo".
If column B contains 5 line items for the same cargo in column C, how do I
get column A to input the next serial number only after contents in Column
C
has changed.