How to create a simple calculator

Question

use a form and a text box in it to show the entered number and use 15 buttons to create numbers and (+,-,/,*) in it.

 

                                                                                                    Calculator form

 

 

    Text Box

 

1	2	3	*
4	5	6	/
7	8	9	-
0	C	=	+

 

 the numbers and signs which have used are buttons of form.

 

Example:

    

 First, When enter a number like 22 means click on 2 two times next, if the user enter one of the (+,-,*,/) wait user to enter second number (like:13)

then,when the user Click on the = button in this case by paying attention to the signs and calculate for example: +  so after calculating  the numbers 22+13 and pushing the = button ,print the result on the text box

Note: If user click on the C button so delete the current number or signs (+,-,*,/).