It can be done but sounds a little dangerous to me.

How do you know if you have typed in the correct code number?

You would be better off using a helper column with a VLOOKUP formula to
return the definition.

The lookup table can be on another sheet.

Easier to error-check because the number as well as the definition will be
visible.

To use event code as you asked, you could use a table on Sheet2 in say
G1:H10

This code would go into the sheet module of Sheet1(your entry sheet)

Private Sub Worksheet_Change(ByVal Target As Range)
Dim ival As String
Dim R As Range
Set R = Range("A1:A100") 'adjust to suit.
If Intersect(Target, R) Is Nothing Then Exit Sub
If Not IsError(Application.Match(Target.Value, _
Sheets("Sheet2").Range("G1:G10"), 0)) Then
ival = Application.VLookup(Target.Value, _
Sheets("Sheet2").Range("G1:H10"), 2, False)
Target.Value = ival
End If
End Sub


Gord Dibben MS Excel MVP
On Fri, 26 Dec 2008 06:06:01 -0800, E-Assistant
wrote:

I am working on huge project where I have to input individual definitions
that have a numerical code for each. What i would like to do is set up a
system that would allow me to just type the code and it automatically be
replaced (w/the same cell) by it's definition. Could macros do this, if so
how or would I need to use a formula, if so which one?