‘decimal number’ does it mean that S evaluates to be like “-034920.20390942” or “+03948.234829300” after the replacements?
don’t worry about -,+. I don’t think there are cases with - or +.
Decimal number means that the number can be represented in Base 10. The decimal point may or may not be there.
can answer be empty string???
no, bcz clearly mentioned that answer is guaranteed to be a decimal number