In digital caliper calibration, which step is performed last?

• A. Press the zero button
• B. Turn on the display
• C. Close the jaws
• D. Check the zero reading

Answer: (A)

The essential idea is to establish a precise zero reference after the jaws are in the known closed position. Start by turning on the display so you can see the reading. Then close the jaws so they touch firmly, giving a clean, exact closed-jaw reference. Saving that reference with the zero button is what finalizes calibration, because it sets the current closed position as zero for all future measurements. That’s why this step is performed last—the act of pressing the zero button locks in the zero point. Turning on the display and closing the jaws do their jobs to prepare the reference, while checking the zero reading is a validation step you can do after zeroing, but the calibration is completed when you press the zero button.