Use Conditional Highlighting in Apple Numbers

Platform and verification boundary

This walkthrough targets Numbers 15.4 for Mac, as identified by Apple’s retrieved guide metadata, reviewed on 19 October 2026. The Mac sidebar/menu instructions do not establish the same controls on iPad, iPhone, or Numbers for iCloud. Older Mac editions can differ. Native Numbers was unavailable to the author: procedures were checked against Apple documentation and fixture expectations were independently calculated; no app execution or product screenshots are claimed.

Build a small exception check in which high readings stand out without changing the readings themselves. You will finish with four values and an auditable rule, then try a separate reference-based comparison.

Create the Readings fixture

Choose File > New and the Blank template. Double-click the sheet tab to give it the name below, and double-click the table title to rename it. If the title is hidden, Control-click row 1 and choose Show Table Title. Use Format > Table to set one header row, zero header columns and zero footer rows unless instructed otherwise. Enter each fixture at the stated cell address; extra empty rows may remain. All examples are invented practice data.

Name the sheet Checks and the table Readings. Enter:

Cell	Entry	Cell	Entry
A1	Sample	B1	Reading
A2	North	B2	92
A3	South	B3	105
A4	East	B4	130
A5	West	B5	87
D1	Limit	D2	100

The four readings total 414; the limit is not part of that total. Keep column C empty to separate the readings from the control value.

Highlight readings above the limit

1. On Checks, select only Readings::B2:B5, excluding the header and control value.
2. Open Format > Cell, click Conditional Highlighting, then Add a Rule.
3. Choose Numbers, then the comparison for values greater than a specified number. Enter 100.
4. Select a conspicuous fill from the style pop-up menu, then click Done.
5. Inspect all four rows. 105 and 130 should receive the style; 92 and 87 should not. The rule does not remove rows, block input, or alter the total.
6. Change B2 to 101. North should now be highlighted; the total is 423. Change B2 back to 92 explicitly to restore the named Readings fixture.

Apple documents the rule controls, cell-reference comparison, rule order, and removal. The rule tests the selected cells individually. A numeric comparison should be tested with actual numbers rather than text that merely resembles numbers.

Save the completed result

With Checks active and the four original readings restored, choose File > Save. Save as Numbers-Readings-Final.numbers in a local Numbers Practice folder, using Where > Other > New Folder if necessary. Close and reopen that exact file. Confirm B2:B5 still reads 92, 105, 130, 87, and only South and East are highlighted. This is the finished deliverable.

Optional experiments in a separate copy

Use File > Save As to create Numbers-Readings-Experiments.numbers in the same folder before changing anything. Confirm the new name in the title bar. Start each branch with the original values above; do not depend on Undo after reopening.

• Reference branch: select B2:B5, open Show Highlighting Rules, and remove the constant rule using its Trash button. Add the same greater-than rule, but use the Cell Reference button to select D2 instead of typing a threshold. Check that the reference is D2 for each tested cell. With D2 at 100, two readings qualify. Change D2 to 110: only 130 qualifies. Restore D2 to 100 before another branch.
• Priority branch: start with the constant greater-than-100 rule only. Add a second greater-than-120 rule with a different fill. B4 matches both. Drag the stricter rule above the first rule to make its style win. First matching rule order determines the appearance; it is not an automatic blend of both styles. Restore one rule before testing growth.
• Growth branch: enter A6 Central and B6 120. Select B5 (which has the original rule) together with B6, then Format > Cell > Show Highlighting Rules > Combine Rules. Check that B6 now highlights and that the threshold is still 100. The five readings total 534. Explicitly applying the rule avoids assuming that a new row inherited it.

Troubleshooting and cleanup

If every value changes color, confirm the comparison direction and that the number is 100, not 10. If 100 itself highlights, check whether you selected greater-than-or-equal rather than strict greater-than. If one cell behaves differently, inspect its own rules and data type. For overlapping rules, check their order before changing the numbers. To clear the experiments, select the test cells and choose Clear All Rules from the rules pane’s advanced menu, or discard only the experiment copy. Keep the final file intact.

Sources and practice-file setup

The source scope is Use cell conditions in Numbers on Mac. The cited Apple guide pages identify Numbers 15.4 in their metadata. Create a spreadsheet, name the sheet, name the table, set headers and table rows and save a named spreadsheet or separate copy support the common setup and save steps.