Dim cmd As ADODB.Command
    Set cmd = New ADODB.Command
    With cmd
        .ActiveConnection = CurrentProject.Connection
        .CommandText =  "create table tab1(f1 numeric(18 , 3 )) "
        .CommandType = adCmdText
        .Execute , , adExecuteNoRecords
    End With

The data types listed in the previous SQL statement can be executed only through 
the Jet OLE DB provider and ADO. They will result in an error message if used 
through the Access SQL View user interface. Also note that if you create a field 
with the NUMERIC data type through the Access SQL View, it will result in a 
DOUBLE data type when you view the table design through the Access user 
interface. But if you create the NUMERIC data type through the Jet OLE DB 
provider and ADO, it will result in a data type of DECIMAL when you view the table 
design through the Access user interface.