Execute analytical mathematical calculations

I have the quarter's analytical calculations ready for review; send the workbook to Hana in analytics and then to Omar, the finance director, for sign-off by Wednesday. Before sending, ensure every derived cell shows the formula, confirm units are consistent across sheets, and add a one-line justification where a rounding rule or approximation is applied.

Before I deliver the calculation workbook to stakeholders, make the math easy to audit: surface the final formulas for the three headline KPIs on the summary tab, create a small worked example that shows the calculation with real numbers, and flag any steps that use approximation or external lookup tables that a reviewer should verify.

One KPI from my spreadsheet disagrees with the controller's report and the controller says my number can't be right; I checked formulas but I don't know whether the mismatch is due to a different rounding rule, a timing cut-off, or a hidden filter. I need to respond to the controller and preserve credibility. What precise checks should I run in order and the most probable cause?

I keep losing time each week tracing small formula errors and explaining them to managers; the same mistakes appear in multiple files and damage my credibility. What single naming convention, one protection I should enable in workbooks, and one review ritual will reduce these recurring calculation errors?