|the closest you can get is vbscript, which is native to windows. You can write your own calculator using whatever degree of elaboration you have the patience for.|
here's a simple one (calc.vbs):
select case op
and call it like this (to capture the answer to a var):
for /f %%a in ('cscript /b calc.vbs 12.6 / 18.2') do set xx=%%a
I was lazy and used separate arguments, so the spaces required between the numbers and operators.
of course you can add as many other operators as you want:
modulo, exponentiation, square roots, etc etc.
I wish cscript could be compiled into .exe, but alas...
i saw some for download but they were either "trials" or $$.