App is stooped unfortunately, When i click Multiplication and division buttons.

[anilreddypu]

when i am running calculator program in android studio emulator, the app is stooping unfortunately.
When i work with addition and subtraction, the app works very fine but if i click Multiplication or division. I am getting the error unfortunately the app is stopped.
Please give me the solution.
Thanks in advance...!

[abdalqaderba]

I solved this problem with minor modifications
many sweet in your programming style