calculator (+, -, *, /)

Continuous calculator with output value.

How to use?

1. Input starting number.
2. Input operator.
3. Input next number.
4. Decide whether keep calculate with result or finish.

How it works?

This program stores user's input to a dictionary. When the calculated result is obtained, the value of user input is replaced with new result. It allows to continue to calculate with newly gained result.