Correct it as soon as you notice it and tell the interviewer exactly which downstream number changes.

Trying to hide the error usually creates more confusion than a short, controlled correction.

If 12% was accidentally treated as 10%, go back to that step, recompute the affected result, and preserve any unaffected logic.

Practice verbal corrections so the recovery itself feels routine rather than dramatic. You can also use this CaseBasix guide for a structured review.

What helped me was writing the equation first. Once I could see the steps, the recovery felt much less stressful.