this is how it should be sir...

1. Basic Calculator
2. Days
3. Positive or Negative
4. odd or even
please enter that number that u want to use:
then when they chose 1 the basic calculator must be seem lyk this

Enter the first number: x
Enter the second number: x

The sum is: x
The difference is: x
The product is: x
Then quotient is: x
and then it will ask them

would you like to use it again yes or no