ISNUMBER
Quirk foundCategory: Information · Last tested 2026-07-04
Support matrix
| Engine | Documented | Live-tested | Verdict |
|---|---|---|---|
| Excel | Yes | Not yet | n/a |
| Google Sheets | Yes | Not yet | n/a |
| LibreOffice Calc | Yes | Yes (24.2.7.2, 2026-07-04) | Quirk found |
Discovered quirks
- =ISNUMBER(TRUE) on LibreOffice Calc returned True, but the documented/expected result is False. ISNUMBER(TRUE) = FALSE; use ISLOGICAL to detect booleans instead.; MISMATCH vs expected: expected False, got True
Executed test cases
LibreOffice Calc 24.2.7.2 (tested 2026-07-04)
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ISNUMBER(A1) | A genuine number -> TRUE | True | True | Matched |
| =ISNUMBER(A1) | A text string -> FALSE | False | False | Matched |
| =ISNUMBER(TRUE) | Documented divergence/point of confusion: a logical TRUE/FALSE value is its own distinct type in Excel's IS-function type system and is NOT considered a number, even though it participates in arithmetic as 1/0. Microsoft's IS-functions page (https://support.microsoft.com/en-us/office/is-functions-0f2d7971-6019-40a0-a171-f2d869135665) states value arguments 'are not converted' and gives ISLOGICAL as the dedicated test for booleans, distinct from ISNUMBER -- the docs do not give an explicit ISNUMBER(TRUE) example, but this is the well-established, widely verified real Excel result. | True | False ISNUMBER(TRUE) = FALSE; use ISLOGICAL to detect booleans instead. |
Mismatch |
| =ISNUMBER(A1) | A blank cell -> FALSE | False | False | Matched |
Docs & syntax
- Excel: official documentation
- Google Sheets: official documentation
- LibreOffice Calc: official documentation