This machine has been sorting for twenty years and nobody has seen the instruction sheet since. The only sure thing is that it always decides the same way: the same card always falls into the same bin.
When you think you know why, ask for the exam: it'll give you five cards you haven't seen and you'll have to say where each one falls. All five.
| band | sym. | no. | notches | bin |
|---|
It swallows punched cards and drops them into one of two bins. Nobody in the office knows the rule anymore, and without that rule the census can't be certified. You have thirty blank cards to punch however you like and a machine that only answers yes or no. Work out the rule.
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