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Compare buying and leasing a machine over three years

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

About this exercise

You're comparing two ways to get a machine for the operations manager. Write a prompt for a markdown table with columns Option, Cash out, Resale and Net 3-year cost for three rows: Buy (with resale), Buy (no resale), Lease. Show the math for Buy's cash out. After the table add one line starting "Difference:" comparing Lease with both Buy rows. Facts only: no recommendation. Under 120 words.

Common mistakes when you ask AI for this

  • Dropping the no-resale case. The AI relies on the estimated resale value. Try: Say: "Show Buy both with and without resale."
  • Forgetting maintenance. The AI uses $30,000 for Buy. Try: Add: "Buy cash out includes 3 years of maintenance."
  • Skipping the lease math. The AI writes $32,400 with no multiplication. Try: Add: "Show 36 x $900 for the lease."
  • Adding advice. The AI recommends one option or comments on taxes. Try: Add: "Facts only; no recommendation and no tax comments."
  • Trusting the AI to count words. AI is bad at counting and runs past word limits. Try: Ask for fewer words than the real cap and keep each part short.

What a strong prompt includes

  • Names the columns
  • Lists the three rows
  • Asks for the math
  • Bans a recommendation
  • Caps length

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