Time: 0:00
This is a type errors bug
Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.
Everything typed into a form, or read with input(), arrives as a string, even when it looks like a number. "20" + 1 is not arithmetic: + on a string means joining text, and Python refuses to join a string to an integer rather than guess what you meant. Convert at the boundary, as soon as the value enters your program, with int() or float(). The error message names both types, which tells you exactly which side needs converting.
The pattern behind it: type errors.
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