If you arrange your buttons in a vertical list, you can resize the field to make it so narrow that the values selected are not visible to the user:
can then look like:
 Very Good
where the text shown is either layout text or muliple lines of text in a parallel field. Then your user can click the button to the left of "Excellent" but the radio button field records 100 as it's value.
You can also use this case function in a separate calculation field to convert the text into numbers:
Case ( RadiobuttonField = "Excellent" ; 100 ;
RadiobuttonField = "very Good" ; 75 ;
RadiobuttonField = "Good" ; 50;
RadiobuttonField = "fair" ; 25 ;
RadiobuttonField = "poor" ; 0;
A third option is to create a table of these 5 text values with a second field that records the number value. Then a looked up value setting on a Number field in your original table can copy the matching number value from this table when a value is selected in the radio button field. This third option makes for easier updates should you later deside to change either the radio button text terms or their matching number values.