I have this code that works

Sub NAMEINLAP1()
Dim t As Integer

With Worksheets("cardata1").Activate
ActiveSheet.Range("a1:h500").Select
For Each c In Selection.Columns(1).Range("a2:a20")
If Not IsNumeric(c) Then c.Offset(, 1) = "IN LAP"
Next
End Sub

However I want to loop it through 26 sheets in the format "cardata" & i
so i tried this;

Sub NAMEINLAP1()
Dim t As Integer
Dim i As Integer

For i = 1 To 26
With Worksheets("cardata" & i).Activate
ActiveSheet.Range("a1:h500").Select
For Each c In Selection.Columns(1).Range("a2:a20")
If Not IsNumeric(c) Then c.Offset(, 1) = "IN LAP"
Nextc
Next i

End Sub

However there is a problem with this. I guess it is to do with the
double for/next statements but I am not sure of an alternative.

Many thanks for your help.