Under the assumption you’re doing this in excel (sorry if not);
Read the range to the datatable, then at the beginning of each ‘for each row’ loop increment a counter by 1. Note - if you are adding headers to the DT then you should initialize the counter at 1, so that the first row it reads will be recognized as row 2 of the spreadsheet. If you are not adding headers, initialize the counter at 0.
When it finds a matching row, add a break to come out of the loop, and then read cell - “A”+(yourCounter+1).ToString (assuming the value you need to read is in col A).
This will read the cell in the row after the last one processed during the for each loop.