Examples

•  "One Thousand Five Hundred" =~ "(T[^ ]+)"
     returns: Thousand
  
   "One Thousand Five Hundred" =~ "T[^ ]+"
     returns: 8
  
   "One Thousand Five Hundred" : "T[^ ]+"
     returns: 0
  
   "8015551212" : "(...)"
     returns: 801
  
   "3075551212":"...(...)"
     returns: 555
  
   ! "One Thousand Five Hundred" =~ "T[^ ]+"
     returns: 0 (because it applies to the string, which is non-null,
                      which it turns to "0", and then looks for the pattern
                      in the "0", and doesn't find it)
  
   !( "One Thousand Five Hundred" : "T[^ ]+" )
     returns: 1  (because the string doesn't start with a word starting
                       with T, so the match evals to 0, and the ! operator
                       inverts it to 1 ).
  
   2 + 8 / 2
     returns 6. (because of operator precedence; the division is done first, then the addition).
  
   2+8/2
     returns 6. Spaces aren't necessary.
  
  (2+8)/2
     returns 5, of course.
  
  (3+8)/2
     returns 5.5 now.
  
  TRUNC((3+8)/2)
     returns 5.
  
  FLOOR(2.5)
     returns 2
  
  FLOOR(-2.5)
     returns -3
  
  CEIL(2.5)
     returns 3.
  
  CEIL(-2.5)
     returns -2.
  
  ROUND(2.5)
     returns 3.
  
  ROUND(3.5)
     returns 4.
  
  ROUND(-2.5)
     returns -3
  
  RINT(2.5)
     returns 2.
  
  RINT(3.5)
     returns 4.
  
  RINT(-2.5)
     returns -2.
  
  RINT(-3.5)
     returns -4.
  
  TRUNC(2.5)
     returns 2.
  
  TRUNC(3.5)
     returns 3.
  
  TRUNC(-3.5)
     returns -3.
  

Of course, all of the above examples use constants, but would work the same if any of the numeric or string constants were replaced with a variable reference ${CALLERID(num)}, for instance.