Improper input after server unreachable

[Vishal Gaurav]

The calculator only takes single digit number as first input after server unreadable.

Steps to reproduce-

1. run Calculator.py
2. enter sum expression(ex - 9/9), we get 'Server Unreachable... output in calculator
3. press clear button
4. run CalculatorServer.py
5. enter some expression(ex- 111+11), we get to see correct output.
6. press clear button
7. now try inputting more than one numeral for input, it doesn't works.