Try putting this into the worksheet code where you want this to occur, the
input cell is A1 the summation cell is B1

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Range("A1").Value 0 Then
Range("B1").Value = Range("B1").Value + Range("A1").Value
Range("A1").Value = ""
End If
End Sub

Cheers
Nigel

"Raymond" wrote in message
...
I want to enter a number into a cell and this number will automatically
add
its value into another cell. However, after the pressing the enter key, I
want the entered number to be disappeared, leaving room for the next
number.
How can I accomplish this? Or is this possible?