Calculation Issues

Why Excel Calculates -399 Squared Incorrectly and How to Fix It

Kushani Nimanthika Sep 27, 2026 869 views

Question details

The user is experiencing a calculation discrepancy where squaring a cell that displays -399 yields 159227 instead of the expected 159201.

Why Excel Calculates -399² Incorrectly and How to Fix It

Product: Excel
Device & OS: not provided
Scenario: Performing mathematical squaring operations on cells that appear to contain whole numbers but actually contain hidden decimals.
Observed behavior: Excel returns a result based on the full stored decimal value (e.g., -399.03258...) rather than the integer value displayed in the cell.

Before you start

Before modifying your formulas, identify the exact cell containing the base number and ensure your workbook calculation is set to Automatic.

Solution 1Recommended

Reveal the Full Stored Decimal Value

Adjust the cell formatting and column width to display the actual underlying number Excel is using for its calculations.

Excel retains up to 15 significant digits of precision for calculations, even if the cell is formatted to show no decimal places. The discrepancy occurs because Excel squares the exact stored value, not the rounded number visible on your screen.

Select the Target Cell

Click on the cell containing the base number that appears as -399.

Change Cell Format to General

Navigate to the Home tab on the Excel ribbon, locate the Number format dropdown menu, and change the format from 'Number' to 'General'.

Widen the Column

Hover your mouse over the right boundary of the column header (e.g., between D and E) and double-click to automatically expand the column width. You will now see the exact decimal value, such as -399.032580123478.

Calculation Verified: Once the full decimal value is revealed, you will see that squaring that exact number mathematically results in 159227.

Solution 2

Calculate Based on the Displayed Value Using ROUND

Use the ROUND function if you strictly want Excel to calculate the square based on the integer value displayed in the cell.

Seamless Data Calculation

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WPS Office Spreadsheet provides intuitive cell formatting tools and powerful mathematical functions to handle complex calculations. It seamlessly handles exact calculation methods to prevent rounding discrepancies in your reports.

1. Open Your Spreadsheet: Launch WPS Spreadsheet and open the workbook containing the calculation discrepancy.
2. Access Format Cells: Right-click the cell displaying the rounded number and select 'Format Cells', or press Ctrl+1.
3. Apply General Format: Under the Number tab, select 'General' and click OK to display the true underlying decimal value.

Fully compatible with Microsoft Excel file formats, including XLSX and XLS.Accurately handles stored vs. displayed decimal calculations to guarantee data integrity.Intuitive formatting menu allows you to quickly reveal hidden decimals.Lightweight, fast, and completely free to use for your daily office needs.

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Frequently Asked Questions

Why do my Excel totals not match my manual calculator totals?

This happens because Excel calculates sums based on the exact stored values (which may include hidden decimals up to 15 places), while you are manually calculating based on the rounded numbers displayed on your screen.

How can I force Excel to use the visible numbers for calculation?

You can use the ROUND function within your formulas to trim decimals, or navigate to File > Options > Advanced, scroll to 'When calculating this workbook', and check 'Set precision as displayed'. Note that the latter permanently alters your stored data.

Does formatting a cell as a whole number change its actual value?

No, changing the cell format to show zero decimal places only changes how the number is visually displayed. The underlying data remains intact with all its original decimal places and will still be used in calculations.

Excel & Data Problems