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They don't have to know that it's a real number. Knowing that you never stop writing nines is sufficient to perform the calculation.
by brlewis 6y ago
They don't have to know that it's a real number. Knowing that you never stop writing nines is sufficient to perform the calculation.
- gspr 6y agoYou're asking them to perform subtraction. They probably know how to do that with real numbers, but problably not with much else. So they'll have to know that they're real numbers (or whatever numbers you are demanding that they be – you're still unclear on this point if it's not actually the reals).
- brlewis 6y agoInternally I'm saying they're real numbers. In what I say to the person trying to intuit that 0.999... = 1, I'm deliberately avoiding talking about number systems. I'm assuming this person thinks of numbers as sequences of digits, possibly with a decimal point.
- gspr 6y agoAnd that is where it all goes wrong.