Step 1: Open any Excel file or the file you need to fix and click on File .
How to fix the error of the Sum function not adding in Excel successfully Picture 1
Step 2: In the Menu, select Options to enter Excel Options.
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Step 3: In Excel Options, select Formulas in the Calculation Options section . Now select Automatic mode and then OK again.
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After activating the automatic calculation mode, not only the SUM function but also other calculation functions in Excel will work normally. Especially, if you are a beginner with Excel, mastering the calculation functions will help increase work efficiency. You can refer to other calculation functions in Excel to get familiar with the spreadsheet.