Counting Bar Codes

[JNB]

I am trying to construct a simpel spreadsheet for capturing cycle counts of inventory. The spreadsheet easily captures the scan of the location and item number via a handheld barcode reader. My issue is that I would like to then allow the user to scan the item barcodes on each box and have excel count those scans. Any ideas on how to format the On-Hand Count column so it counts the scan rather than returning the item number each time? Thank you!

Below is a simple example of the layout
[TABLE="width: 500"]
<TBODY>[TR]
[TD]Location[/TD]
[TD]Item Number[/TD]
[TD]On-Hand Count[/TD]
[/TR]
[TR]
[TD]xx-xx-xx[/TD]
[TD]abc123[/TD]
[TD]15[/TD]
[/TR]
</TBODY>[/TABLE]