04-14: Safe Math Calculator

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A command-line calculator built around custom exception classes. Demonstrates try/except/else/finally and the raise statement. Handles division by zero, invalid input, negative square roots, and unsupported operations through a clean exception hierarchy.

Topics covered: custom exception classes · raise · try/except/else/finally · exception inheritance · math.sqrt() · while-loop menu · functions · calculation history

Difficulty: ⭐⭐ Beginner–Intermediate

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How to Run

python main.py

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Exception Hierarchy

Exception
└── CalculatorError
    ├── DivisionByZeroError
    ├── InvalidInputError
    ├── NegativeSquareRootError
    └── UnsupportedOperationError

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Sample Session

Choose: 4
  First number : 10
  Second number: 0

  ❌ Math Error: Cannot divide 10 by zero.

Choose: 8
  First number : -9

  ❌ Math Error: Cannot take square root of negative number (-9.0).

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Key Concepts Practised

Concept	Where used
Custom exception class	DivisionByZeroError(CalculatorError)
raise ExceptionClass(args)	Inside divide(), square_root() etc.
try/except specific type	except DivisionByZeroError as e:
else clause	Runs only when no exception raised
finally clause	Always runs — cleanup pattern