Can you find a way to make:
6 5 4 3 = 81
by concatenation and/or adding any of (and only) these mathematical operators:
- standard parentheses ()
You cannot add other numbers to the equation, or re-order the existing numbers.
The result must be a mathematical equality.
Try to do it while only altering the left hand side!
Inspired by Make 5 5 5 5 = 19
Hopefully somewhat more challenging than my previous attempt (may be hard not to be!)