Break the calculation into sequential steps and label the base after each change. Avoid combining several percentages mentally in one jump.

Percentage changes are easy to confuse because each one may apply to a different base. Writing an intermediate value protects you from compounding errors.

For example, start with revenue, apply the price change, then volume, then calculate margin on the resulting revenue if that is what the prompt asks.

Say the sequence out loud before calculating. This takes a few seconds and often saves a full restart. For a related reference, see Case Interview Mental Math.

This is where keeping notes simple helps. I can see the logic better when I am not writing full sentences.

I had the same concern before recruiting. Once I practiced the exact situation a few times, it felt much less awkward.

I would test this in a couple of mocks with different partners. If the same feedback keeps showing up, then it is probably a real pattern.

I would keep a backup plan in mind, especially for anything involving recruiting logistics. It reduces the stress if the first option changes.

This is where keeping notes simple helps. I can see the logic better when I am not writing full sentences.