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Split a utilities bill when a roommate moved in mid-month
Practice: Giving the right context. About 5 minutes.
About this exercise
You're splitting October utilities among 3 roommates. Jae moved in on Oct 16, so he pays half a share; Alex and Sam pay full shares. Sam's internet upgrade is his alone. Write exactly 3 numbered lines, one per roommate, each showing the math, for a group chat. Plain text, under 60 words, nothing else.
Common mistakes when you ask AI for this
- Splitting evenly. The AI doesn't know Jae moved in mid-month, so it splits $225 three ways at $75. Try: Add: "Jae moved in Oct 16, so he pays half a share."
- Sharing the upgrade. The AI spreads Sam's $15 upgrade across everyone. Try: Add: "Sam pays the $15 upgrade alone; split the other $210."
- Not asking to see the work. Roommates will question a bare number. Try: Add a line to copy: "1. Alex: $210 ÷ 2.5 = $84"
- 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 line: "each line under 14 words."
- Forgetting where it goes. AI loves markdown tables and bold, which show up as clutter in a group chat. Try: Add: "Plain text, no bold, headings or tables."
What a strong prompt includes
- Explains the half share
- Handles the upgrade
- Asks to show the math
- Sets a word limit
- Asks for plain text
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