Calculate CAC payback in months with each step shown

About this exercise

Your CFO asks how many months it takes to earn back what you spend to win a customer. Write exactly 4 numbered lines with the math shown: 1 CAC, 2 monthly gross profit per customer, 3 payback in months, 4 a verdict against the 12-month target. Plain text, under 90 words, round months to one decimal. Use the average discounted price, not the list price.

Common mistakes when you ask AI for this

• Using the list price. The AI uses $80, giving a payback of 8.3 months. Try: Add: "Use the $60 price actually paid, not the $80 list price."
• Skipping steps. The AI jumps to the payback figure. Try: Add: "Show CAC, monthly gross profit, payback, then the verdict, each with its math."
• No verdict. The AI never compares the result to the 12-month target. Try: Add: "Line 4: within or over the 12-month target."
• Leaving the format to chance. The AI picks its own length and layout unless told the exact shape. Try: Add: "Exactly 4 numbered lines. Plain text, no bold or headings."
• Trusting the AI to count words. AI is bad at counting. Ask for a total word limit and it often lands over it. Try: Cap each part instead, for example "each line under 15 words."

What a strong prompt includes

• Asks for four steps
• Uses the paid price
• Shows the math
• Asks for a verdict
• Rules out notes

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