CREATE CALCULATOR USING NOTEPAD

 OPEN NOTEPAD AND WRITE THIS CODE::

@echo off
title Batch Calculator by niksdhags.blogspot.com
color 1f
:top
echo --------------------------------------------------------------
echo Welcome to Batch Calculator by nikhil sonejee
echo --------------------------------------------------------------
echo.
set /p udefine=
set /a udefine=%udefine%
echo.
echo = %udefine%
echo --------------------------------------------------------------
pause
cls
echo Previous Answer: %udefine%
goto top
pause
exit

SAVE AS "FILENAME".BAT (BATCH  EXTENSION)