Four digit keys are swapped in two pairs. Ask for just three sums. Identify both swaps.
Collect evidence
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Possible wirings
Example: with 1↔7 and 3↔8, typing 12+34 computes 72+84. The output digits are not swapped. Exactly four distinct digits change.
Question log
How can the calculator choose its answers?
There is no fixed culprit at the start. Each answer keeps the largest group of wirings consistent with every previous answer. Force exactly one wiring to remain, then name both swaps. Leading zeros are read as ordinary numbers. No time limit; paper and pencil are welcome.
This game tests question design and deduction, not mental arithmetic speed or IQ.
Calculator Interrogation: rules and deduction strategies
Four distinct digits from 0 to 9 are swapped in two pairs. With 1↔7 and 3↔8, typing 12+34 makes the calculator read 72+84 and return 156. Output digits are not swapped again. The remaining six digit keys work normally.
There is no fixed culprit at the start. For each question it groups the wirings consistent with all earlier answers, then chooses the answer retaining the largest group. Ties use the lowest answer. It never discards earlier evidence. You must force a unique wiring and correctly name it to win.