VBA coding in excel

Hi ,

I need coding for the below criteria

In column Q has values like "313380886 , 313380887, 313381958, 4051226810, 4051223695".

I want the VBA coding in column CK that if in column q range value begins with 3 then column CK should be Revenue.

if in column q range value begins with 4 then column CK should be internal.

out put

Column Q     Column CK

313380886  Revenue

313380887  Revenue

313381958  Revenue

4051226810  Internal

4051223695  Internal

please help me with the VBA coding as the list will be more