Attach the currency and period to every value
The fictional offers are A: HK$800 per month and B: US$100 per month. No exchange rate, tax or one-off fee is supplied. The amounts are invented and do not represent vendor prices.
| Supplied evidence | Question or input | Expected result |
|---|---|---|
| A: HK$800/month; B: US$100/month | What is the combined monthly total? | Keep HK$800 and US$100 separate; no single-currency total can be derived |
| A is HK$800/month for 12 unchanged months | What is A’s annual recurring amount? | HK$9,600 before any unspecified fees |
| No currency supplied for “100” | Is 100 cheaper than HK$800? | Ask for the currency and matching period before comparison |
Separate arithmetic from missing assumptions
The answer says “Total 900 per month” after adding 800 and 100. What fails?
Show the worked answer
It merges HKD and USD and removes the currency labels. The integer addition is correct, but the monetary result is not defined by the supplied evidence.
For an eventual conversion test, supply the exact rate, direction, date and rounding rule as fixture inputs. Check the converted result separately from the original amounts. This sheet neither retrieves live rates nor provides financial guidance.