Spreadsheet formulas versus LLMs: separate deterministic calculation from text judgment
Compare rule-based calculation with open-ended text processing, checking formula preservation, changed inputs and recalculation.
Choose an approach
Use inspectable formulas or programs for defined calculations and LLMs for interpreting, classifying or rewriting text. Models can draft formulas, but the spreadsheet engine should execute and verify them. Do not replace formulas with one generated value; changed inputs must still update correctly.
Recalculable rules differ from generated text
Excel formulas express rules through functions and references; LLMs generate outputs. A correct generated number does not create a recalculating dependency. Models can explain or draft formulas, then references and empty cases need checks. Text labels need defined categories and unknowns. Separate input, formula and writable result columns before bulk changes to protect existing calculations.
Change inputs in the same workbook to test recalculation
Use a test copy containing formulas and identical data for both approaches. Check current outputs, change an input and confirm formulas remain and recalculate. Inspect model writes for overwritten cells and classifications against known labels. Independently recalculate amounts instead of asking the same model to endorse itself. No actual workbook or model call was used and no automation success rate is given.
Protect formula ranges and preserve evidence
Version formulas and references alongside prompts and labels. Keep deterministic calculations in explicit rules for diagnosis while checking business correctness. Include recalculation and overwritten-cell repair in cost. Deliver a reusable workbook and instructions and test appended data rather than only a correct-looking screenshot.
Checked sources
These sources support the concepts and methods described here. Examples and test scope are labeled separately; check the version of the tools you use.