Sunday, January 31, 2010

Equal or Not?

I stumbled across an apparently-classic mathematical discrepancy, and decided to share the question along with my attempt at a logical solution/response.

"Is the decimal 0.999..., where there are an infinite number of 9's, equal to 1?"

Along with the question, I saw countless proofs, counterproofs, and and everything inbetween on the subject. My personal opinion is that the prior is an improperly-expressed equivalent of the latter. Given that 1/9 = 0.111..., multiplying the fraction by nine would give us 9/9, or 1. But, multiplying the decimal by 9 simply multiplies all the individual digits by 9, giving us the ambiguous 0.999... . Technically, they should yield the same value, yet the decimal is not the same as 1. 0.111... is a decimal APPROXIMATION for 1/9. Multiplying either the fraction or decimal representation of said fraction will yield 1, not 0.999... . On another point, try and find me a number between 0.999..., where there are an infinite number of 9's, and 1. There isn't one, because they're the same number: 1.

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