Getting info from a cell after the last letter appears...

This should do it:

Option Explicit

Public Sub Test()
  Dim x As Long
  
  x = GetNumber("24Macros113")
End Sub

Public Function GetNumber(x As String) As Long
  Dim NumberLength As Long
  
  NumberLength = 1
  
  Do While IsNumeric(Right(x, NumberLength))
    NumberLength = NumberLength + 1
  Loop
  GetNumber = CLng(Right(x, NumberLength - 1))
End Function