Using Python, write a software application based on a real-world problem. Make sure to provide notes within the code, to understand what is happening in each section.

The requirements are below: You should have a total of 7 concepts utilized. This just needs to provide output, no fancy GUI or anything to that nature.

Pick Three:

> Numberic Calculations

> Variable Operators

> Mathematic Calculations

> Exception Handling

Pick Three:

> String Manipulation

> Decision Structures

> Repetitive Logic

> Functions

> Classes

Pick ONE:

> External Data

> MySQL Database