I have a large excel of purchase orders where i need to add all the quantities of unique part numbers. I am trying to search the entire excel file, and add the quantities if they are a specific part number.
Example:

Part Number QTY
364 7
364 11
373 6
373 8
373 54
334 8
334 2

I want to be able to create a function with the part number and all data as an input that spits out the total for selected part number. For example, if i wanted to find the total quantity of 364 i would type into excel:
QtyPerPN(364, A2:B8) would return 18.

How do i make the QtyPerPN() function correctly?

Function QtyPerPN(PartNumber, PN_QTYRange() As Variant)

 Dim TotalQty, counter
 TotalQty = 0
 counter = 0

 Dim i As Long
 i = 0

 Do While counter < 15
 '15 is just for testing on small set amount of data
    counter = counter + 1
        If PartNumber = PN_QTYRange(i) Then
            TotalQty = TotalQty + PN_QTYRange(i, i)
            i = i + 1
        End If
    Loop

 QtyPerPN = TotalQty

End Function