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Build a CAC, LTV and payback table by channel

  • For FP&A and financial analysts
  • You practice Asking for a format you can use
  • Time about 5 minutes
  • Level Intermediate

About this exercise

Marketing wants unit economics by acquisition channel for Q3. Make one table with exactly these columns in order: Channel | CAC | LTV | Payback (months). Use the corrected Events spend. Under the table, add one line starting "Formulas:" that states how each column was calculated. No bold anywhere, under 80 words.

Common mistakes when you ask AI for this

  • Using the first Events number. The AI uses the table figure and misses the refund correction further down. Try: Add: "Use the corrected Events spend of $40,000."
  • Not fixing the formulas. The AI picks its own LTV formula, sometimes leaving out margin. Try: Spell it out: "LTV = ARPA × gross margin ÷ monthly churn."
  • Letting it design the table. The AI adds columns like LTV:CAC and spend, and writes paragraphs around it. Try: Say: "Columns exactly: Channel | CAC | LTV | Payback (months). Then one 'Formulas:' line."
  • Forgetting where it goes. AI adds bold and headings, which show up as ** and # clutter in email and chat. Try: Add: "Plain text only, no bold, no headings."
  • Trusting the AI to count words. AI is bad at counting and usually runs long on finance write-ups. Try: Cap each part instead: "each line under 15 words" so the total stays well under 80.

What a strong prompt includes

  • Names the exact columns
  • Uses the correction
  • Gives the formulas
  • Bans bold
  • Sets a length limit

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