How have you used Excel in your work, and what is the most complex thing you have built in it?

Note: Everyone claims to know Excel. The interviewer is trying to find out whether you use it as a grid or as a tool. Describe something with structure, not just formatting.

Give:

• The business purpose. A budget model, a reconciliation, a reporting pack, a forecast, or a tracker used by a team.
• The scale. Number of rows, number of source files, how many people used it, and how often it ran. "A model consolidating twelve regional files monthly" is concrete.
• What made it non-trivial. Strong answers: Power Query pulling and cleaning from multiple sources, a Power Pivot data model with DAX measures, scenario analysis with data tables, or a validated input sheet that stopped users breaking it.
• The outcome — hours saved, errors eliminated, or a decision it enabled.

Being able to say "I later moved it out of Excel because it had outgrown it" is a strong sign of judgement.