Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
You expect a total, but Python stops with a TypeError: unsupported operand types for addition. A common cause is trying to combine text and a number, such as adding the string "12" to the integer 3. Before changing the line, trace where each value came from.
Find the Line That Failed
Read the traceback from the bottom for the error message, then look upward for the file and line where your code made the failing operation. If that line says total = amount + fee, inspect both amount and fee rather than assuming the addition itself is wrong. The traceback identifies where Python stopped; it doesn’t always identify where the unexpected value first entered your program.
Inspect the Values
Temporarily print type(amount) and type(fee) just before the operation, along with their values if they contain no sensitive information. Data read from a text file, form, or CSV often arrives as a string, even when it looks numeric on screen. That distinction is easy to miss when the value is printed as 12 rather than shown with quotation marks.
Convert With Intent
If the value represents a whole number, converting it with int(amount) may be appropriate; for decimal values, consider float(amount) instead. For example, total = int("12") + 3 evaluates to 15, while adding the original string to 3 raises the error. Conversion can also fail when input contains blanks or non-numeric text, so decide how your program should handle those cases and test them. Remove temporary print statements once you have confirmed the fix.
Bestseller #1
Bestseller #2
Bestseller #3
