Get a mortgage payment formula you can explain to buyers

About this exercise

You want a buyer-facing sheet where C2 shows the monthly principal-and-interest payment as a positive number, from the loan amount in A2, the yearly rate in B2 and a 30-year term. Ask for one formula for C2 in one code block, then exactly 2 numbered lines labeled Means: (plain words for a first-time buyer, no function names) and Check: (the payment for $400,000 at 6%). Under 50 words outside the code.

Common mistakes when you ask AI for this

• Leaving the term vague. The AI uses the yearly rate and 30 periods, the same mistake as your first try. Try: Add: "Monthly payment: rate / 12, 360 months."
• Not asking for a positive number. Excel shows loan payments as negative, which scares buyers. Try: Add: "Show it as a positive number."
• Explaining to the wrong reader. The AI explains PMT arguments, which means nothing to a buyer. Try: Add: "Means: plain words for a first-time buyer, no function names."
• Getting a menu of options. The AI likes to offer two or three versions of the formula, so you're left to pick and test them yourself. Try: Add: "Give one formula only, in one code block, no alternatives."
• Getting a tutorial. By default the AI explains every part of the formula at length. Try: Add: "Each line under 20 words. Nothing else."

What a strong prompt includes

• Asks for a monthly payment
• Asks for a positive number
• Says who reads it
• Asks for a check
• Asks for one formula

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