**''<Simple>''** 

''<Simple> == <Digit>'' || ''<Simple> <Digit>'' 

''<Digit> =='' **''0''** || **''1''** || **''2''** || **''3''** || **''4''** || **''5''** || **''6''** || **''7''** || **''8''** || **''9''** 

''<Simple>'' is a simple real number.

One cannot use any randomly generated numbers or interval values for a ''<Simple>''.