Your rules indicate the only operations permitted are concatenation ||, subtraction -, and division /. Is that correct?
[spoiler=Or are these special operations and mathematical notations also permitted?]exponetiation (visually, does not require any special symbols when using simple superscription. The character symbols ^ and ** are only used when superscripting is not an option), tetration (the same is true for this operation, when superscripting the operation is alternately represented by ^^ or Knuth's double arrows. The other notation I inquire is whether one can use base notation.
I am assuming you are using a modified interpretation of the concatenation operator, allowing it to concatenate the result of an operation and not simply two numerals. The operator precedence of the concatenation operator, in regards to the other operators, is last. Does this still hold true for this puzzle?