A variable name in the programming language BASIC† can be either a letter or a letter followed by a decimal digit—that is, one of the numbers 0, 1, . . . , 9.

Question

I have worked this problem several times and cannot figure it out

Answer 1

Let's determine how many possible different variable names the compiler/interpreter may put into the symbol table.

 

There are 26 letters in the English alphabet             --           26 names with one letter

   Each of 10 single digits may follow a letter:   26*10  =      260 names with a letter-digit combination

                                                                                      ------

                                                                                       286 total possible variable names

 

Now, the computer will not care, but a programmer probably should be careful not to select names like:

     O0

     I1

     S5