Step 1 : method was changed
Step 2a: isclearallkey as been added
Step 2b : siresultkey as been added
step 2b: result method added
Step 2c: arithmetic key method added
step 3a: register arithmetic method was added
Step 3b: compute and display result was added
Step 4a: clear operation was added
Step 4b: clean up as been done
step 4c: more clean up was done
step 5: else if statement have been added