I cannot figure this out for the life of me. Allow me to set the stage.

On sheet 1 I will scan in items. On Sheet 2 inventory items will be listed, lets say in column A, and a running total will be kept adjacent to each item in column B. Back on sheet 1, lets say in cell A1, I want to scan in my item number and then I will manually enter a quantity in cell B1. Here's where it gets tough for me. After I input the quantity in cell B1 on Sheet 1 and press enter, I want excel to lookup the scanned item in column A on sheet 2 and add the quantity for it to the running total in Column B and then clear the contents of Cells A1 and B1 on Sheet one with A1 selected and ready to scan in the next item.

I'm not much of a macro man. I have tried all manner of elaborate formulas and arrangements to get a similar functionality with no success. I know the answer has to be in a macro. Please Help! Any solution or direction would be much appreciated.