Please open your notepad and copy the code below
----------------------------code------------------------------
echo off
cls
echo.
echo This is multiplication calculation
set/p "user=FirstNo=>"
set/p "pass=SecondNo=>"
set /a a=%user%*%pass%
echo so the answers is = %a%
pause >nul
---------------------------end code---------------------------

then paste this code in your notepad and save as "calculator.bat"

*note = you can change * with +,- and /