calc

@echo off
setlocal enabledelayedexpansion
if "%1" == "/?" echo Hello! Write numbers and operations. For example 2 + 3. & goto :eof
set x=
set ans=
set x=%1
if  "%1"==""  set /p x=write!
:start
shift
set x=%x% %1
if "%1"=="" (
	set /a ans=!x! 2>nul || set ans=error
	echo !ans!
	endlocal & goto :eof
)
goto :start