MS 365 EXCEL started changing the number format

Question

MS365 Excel converts a whole number to a decimal number in a column formatted as "general." This started after I closed Excel and then opened the spreadsheet again. The cells that were correct when the document was closed remain correct; format painter will not apply the old format to the cells I have added since the document was closed and reopened. I have tried formatting as "general," "text," and "custom." If I put the number in quotes, it keeps the number I typed. A formula will not include the numbers in quotes. This issue now appears across all worksheets, not just the one that was edited before I closed Excel for the day.

Answer 1

Hello Judy PMSI,

The behavior you're seeing almost always comes from an Excel setting that changes how numbers are entered, not from the cell’s number format. In other words: even if the cell is General, Excel can still shift your input into decimals while you type—so Format Painter won’t “fix” it, because the problem isn’t the format. For more information: https://support.microsoft.com/en-us/office/enter-data-manually-in-worksheet-cells-c798181d-d75a-41b1-92ad-6c0800f80038

Before changing anything, do this quick check (it tells you which fix applies): click one of the “wrong” cells and look at the formula bar. If the formula bar shows the decimal-shifted value (example: you typed 2834 but it shows 2.834), it’s the “Fixed decimal” setting. If the formula bar shows the original full number but the cell display looks different, it’s mostly a display/rounding/column-width situation. For reference: https://support.microsoft.com/en-us/office/stop-showing-rounded-numbers-cc86bae9-b48e-48da-906d-e334a440d3ea

My suggestion for you:

1. Turn off “Automatically insert a decimal point” (Fixed decimal)

In Excel, select File.

Select Options.

Select Advanced.

Under Editing options, clear Automatically insert a decimal point.

If there is a Places box showing a number, set it to 0 (or just clearing the checkbox is enough).

Try typing a whole number into a blank cell again to confirm it stays whole.

Tip: If you must leave that setting on for some reason, you can temporarily override it by typing a decimal point as you enter the number.

2. Convert the decimals you already entered back into whole numbers (after turning Fixed decimal off)

If some of your new entries were already shifted (for example, you wanted 1234 but got 12.34), you can undo that in bulk:

First complete Solution 1 to clear Automatically insert a decimal point.

In an empty cell, type 10, 100, or 1,000 depending on how many decimal places were inserted (example: if numbers gained 2 decimals, type 100).

Copy that cell (CTRL+C).

Select the affected cells.

Select the arrow under Paste and choose Paste Special.

Under Operation, choose Multiply.

That multiplication shifts the decimal back to where you intended.

3. Fix display “rounding” in General format

Sometimes Excel is not changing the stored value—only the way it displays it, especially if the column is narrow or decimals are hidden.

Select the affected column.

On the Home tab, select Increase Decimal until the number displays as expected.

If you see #######, auto-fit the column width (double-click the right edge of the column header).

4. Check decimal/thousand separators (less common, but can affect decimal behavior globally)

If something changed at the system/Excel separator level, Excel can interpret input unexpectedly.

Select File > Options > Advanced.

Find Use system separators and confirm it’s set how you expect.

If it’s cleared, verify the Decimal separator and Thousands separator entries.

For reference: https://support.microsoft.com/en-us/office/advanced-options-33244b32-fe79-4579-91a6-48b3be0377c4

I hope this will help with your situation. Please feel free to reach back if you have further update or more questions.

Best Regards,

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Answer 2

Excel’s General format automatically changes how numbers are displayed, which explains the behavior being seen across worksheets.

Key points about General format and decimals:

• General is the default format for new cells.
• When a number is typed in a General-formatted cell, Excel may:
  • Reduce visible decimal places so the value fits in the column, or
  • Switch to scientific notation for large numbers.
• The underlying value is not changed; only the display is adjusted. The full value is still visible in the formula bar and used in calculations.

To stop Excel from changing how the numbers look and to keep full decimals visible:

1. Widen the column if needed
   • If the column is too narrow, Excel may appear to round or shorten the number.
   • Drag the right edge of the column header to make it wider, or double‑click the right border to auto-fit.
2. Increase decimal places explicitly
   • Select the affected cells.
   • On the Home tab, click the Increase Decimal button until the desired number of decimal places is shown.
   • As decimal places are increased, Excel changes the format from General to Number and adjusts the column width automatically.
3. Apply a fixed number format instead of General
   • Select the column or cells.
   • On the Home tab, open the Number format drop-down (or press Ctrl+1 → Number).
   • Choose a format that supports decimals (Number, Currency, Accounting, Percentage, or Scientific) and set the required Decimal places.
   • This prevents Excel from auto-adjusting the display the way General does.

If numbers are stored as text (for example, when quotes are used), they will not behave correctly in formulas. After choosing an appropriate numeric format (such as Number), ensure the entries are real numbers (no quotes) so formulas include them.

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References:

• Reset a number to the General format
• Stop showing rounded numbers
• Available number formats in Excel