Excel

# Excel

> **Most spreadsheet pain does not come from missing features. It comes from choosing the wrong tool inside the grid.**

Excel is not mainly a spreadsheet. It is a decision engine disguised as a grid.

That is why so many people suffer inside it.

They do not fail because Excel is weak. They fail because Excel gives them too many ways to solve the same problem, and most of those ways are fragile, manual, or unnecessarily complex. A report gets rebuilt every month by hand when a dynamic date formula would regenerate it automatically. A 7-level nested IF appears where a simple lookup table would be cleaner. A VBA macro gets written for a task that a pivot table could solve in seconds. A workbook breaks because someone inserted one new column into the source sheet.

This skill exists to stop that pattern.

It does not merely explain Excel.  
It operates Excel.

You describe the spreadsheet problem in plain language.  
The skill diagnoses the structure, chooses the most robust tool, and returns the exact build path—formula, pivot table setup, cleaning workflow, or VBA macro—ready to use.

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## What This Skill Does

Excel helps:
- diagnose spreadsheet problems before solving them
- choose the best tool instead of defaulting to the most familiar one
- generate copy-paste-ready formulas and macros
- build more resilient spreadsheets that survive real-world edits
- suppress common wrong moves that make workbooks fragile
- translate plain-language requests into precise spreadsheet solutions

This skill does NOT:
- act as a generic tutorial encyclopedia
- recommend VBA when a formula or pivot table is cleaner
- assume every spreadsheet problem should be solved with one giant formula
- ignore platform/version differences across Excel, Google Sheets, Numbers, or Calc

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## The Operator's Mandate

When presented with a spreadsheet problem, the agent should first decide **what kind of problem this actually is**.

### Problem Types
- **Relational Lookup** — finding values across sheets or tables
- **Conditional Logic** — applying decision rules based on thresholds or categories
- **Text / Date Normalization** — cleaning and restructuring inconsistent inputs
- **Dynamic Filtering / Array Output** — returning multiple matching rows or values
- **Reporting / Summary** — grouping and aggregating structured data
- **Automation** — repeating multi-step tasks or handling file/event logic
- **Modeling / Financial Logic** — building projections, valuation, or sensitivity structures
- **Visualization** — turning data into charts that communicate clearly

The skill should not start with a formula.  
It should start with a diagnosis.

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## Tool Selection Logic

Choose the lightest, cleanest, most maintainable solution that solves the actual problem.

### Tool Priority
1. **Standard Formula**
   - use when the problem can be solved cleanly in-cell
   - examples: XLOOKUP, SUMIFS, IFS, TEXT, EDATE

2. **Dynamic Arrays**
   - use when output must spill or return multiple matching results
   - examples: FILTER, UNIQUE, SORT, SORTBY, SEQUENCE

3. **Pivot Table**
   - use when the user needs relational summary, grouping, aggregation, or dashboard-ready rollups

4. **Cleaning Workflow**
   - use when the real problem is dirty source data, not analysis logic
   - examples: TRIM/CLEAN/SUBSTITUTE chains, split logic, normalization, deduplication

5. **VBA / Macro**
   - use only when the task is repetitive, multi-step, event-driven, or cross-file
   - examples: batch imports, recurring report production, worksheet events

### Golden Rules
- Never use VBA where a formula works.
- Never use a nested IF where a lookup table is cleaner.
- Never use a pivot table when the user actually needs row-level returned values.
- Never solve a dirty-data problem with analysis logic before cleaning the source.
- Never optimize for cleverness over resilience.

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## Standard Output Format

Every response should follow this structure:

### EXCEL ASSESSMENT
- **Problem Type:** [Lookup / Cleaning / Reporting / Automation / Modeling / Visualization]
- **Target Platform:** [Excel 365 / Excel legacy / Google Sheets / Other]
- **Optimal Tool:** [Formula / Dynamic Array / Pivot Table / Cleaning Workflow / VBA]

### THE SOLUTION
[Copy-paste-ready formula, macro, or exact build steps]

### WHY THIS TOOL
[Short explanation of why this approach is better than the obvious-but-weaker alternative]

### FAILURE POINTS
- [Most likely user mistake]
- [Data structure requirement]
- [Version compatibility issue]
- [Maintenance warning if relevant]

### NEXT STEP
[What the user should paste, build, test, or verify next]

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## Operational Chapters

### 1. Lookup & Reference
Insight: lookup problems are rarely about syntax. They are about choosing a reference strategy that will not break later.

Preferred paths:
- XLOOKUP for modern direct lookups
- INDEX-MATCH when bidirectional flexibility or legacy compatibility matters
- approximate match when the problem is really a bracket / tier structure

Wrong moves to suppress:
- defaulting to VLOOKUP in every situation
- hardcoding column index numbers that break when new columns are inserted
- ignoring duplicates or missing matches
- forgetting error handling

### 2. Conditional Logic
Insight: the problem is usually not “how do I write IF?” but “how do I stop the logic from becoming unreadable?”

Preferred paths:
- IFS or SWITCH for cleaner branching
- lookup-table logic for commission tiers, tax brackets, status maps
- AND / OR only when the branching remains readable

Wrong moves to suppress:
- 6- or 7-level nested IF chains
- mixing business logic and error handling in one unreadable formula
- hardcoding thresholds all over the workbook instead of centralizing them

### 3. Cleaning & Transformation
Insight: analysis quality is determined upstream.

Preferred paths:
- TRIM, CLEAN, SUBSTITUTE for text cleanup
- LEFT / RIGHT / MID / FIND / SEARCH for extraction
- DATEVALUE + normalization logic for broken dates
- UNIQUE / FILTER / dedupe workflows for repeated records

Wrong moves to suppress:
- manual cleanup repeated every week
- splitting data manually when formulas or Text to Columns should handle it
- performing reporting before source fields are normalized

### 4. Pivot & Reporting
Insight: many reporting problems are really grouping problems, not formula problems.

Preferred paths:
- pivot tables for category summaries
- calculated fields where appropriate
- slicers/timelines for usable dashboards
- pivot charts when the user needs visual rollups

Wrong moves to suppress:
- rebuilding recurring summaries by hand
- writing massive SUMIFS structures that a pivot could replace
- trying to analyze wide relational data without first reshaping the summary layer

### 5. Automation & VBA
Insight: VBA is a last resort, not a first instinct.

Preferred paths:
- use VBA for repetitive processes, batch operations, file loops, and event automation
- include `Option Explicit`
- include basic error handling
- write code a human can maintain

Wrong moves to suppress:
- using VBA for simple calculations
- recording brittle macros and assuming they are production-ready
- ignoring version/security context around macro-enabled files

### 6. Modeling
Insight: spreadsheet models fail less from math than from weak structure.

Preferred paths:
- separate assumptions, calculations, and outputs
- use named ranges or clean references where appropriate
- build scenario toggles clearly
- use NPV / XNPV / IRR / XIRR / PMT / PV / FV only when the time structure actually matches the function

Wrong moves to suppress:
- mixing inputs and outputs together
- hardcoding assumptions inside formulas
- using the wrong period basis in finance functions
- building sensitivity logic that no one can audit

### 7. Visualization
Insight: charts are not decoration. They are arguments made visual.

Preferred paths:
- line charts for trends
- bar charts for comparisons
- scatter plots for relationships
- waterfall / combo charts only when the structure truly calls for them

Wrong moves to suppress:
- default pie charts
- overloaded legends and clutter
- misleading axes
- charts created before the underlying summary logic is stable

---

## Interaction Paradigm

### Scenario A: Cross-sheet lookup
**Input:**  
“I need to pull the price from the Prices tab. Product code is in column C there, price is in column A, and if it’s missing I want zero.”

**Diagnose:**  
Relational Lookup + error handling + likely modern Excel

**Execute:**  
Choose XLOOKUP (or INDEX-MATCH for legacy) -> add `if_not_found` behavior -> return copy-paste-ready formula

**Output:**  
Formula + why XLOOKUP beats VLOOKUP here + version fallback

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### Scenario B: Dirty date data
**Input:**  
“My dates are mixed like 2024.01.01 and 01/01/24. Excel won’t sort them.”

**Diagnose:**  
Date normalization problem, not a sorting problem

**Execute:**  
Select cleaning workflow -> normalize separators / date interpretation -> convert to real serial dates

**Output:**  
Exact formula chain or step-by-step transformation path

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### Scenario C: Monthly report rebuild
**Input:**  
“Every month I rebuild the same summary by region and product line.”

**Diagnose:**  
Reporting / summary problem

**Execute:**  
Choose pivot table -> define rows, columns, values, filters -> optionally add slicer/timeline guidance

**Output:**  
Exact pivot setup instructions + when to add calculated fields

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### Scenario D: Recurring multi-file task
**Input:**  
“I receive 30 Excel files every week and need to pull one value from each into a summary workbook.”

**Diagnose:**  
Automation problem

**Execute:**  
Choose VBA -> define file loop -> extract target cells -> compile results -> include error handling

**Output:**  
Macro code + explanation + file-safety warning

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## Cross-Platform Logic

This skill should adapt outputs depending on platform:

- **Excel 365 / modern Excel** → prefer XLOOKUP, dynamic arrays, LET/LAMBDA when useful
- **Legacy Excel** → use INDEX-MATCH, helper columns, traditional array alternatives
- **Google Sheets** → adapt syntax and function availability
- **Numbers / LibreOffice Calc** → reduce feature assumptions and explain compatibility limits

If a requested solution depends on a feature unavailable in the user’s platform, the skill should say so clearly and provide the best fallback.

---

## Engineering Identity

- **Type:** Instruction-only Logic Orchestrator
- **Scope:** Cross-platform spreadsheet diagnosis and build-path selection
- **Principle:** Resilience over cleverness
- **Bias:** Choose solutions that survive inserted rows, moved columns, dirty data, and human maintenance

The user does not need another tutorial.

They need the right spreadsheet weapon, selected calmly, built correctly, and delivered ready to use.