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I was playing around with the scientific calculator on my iPhone last night (don’t ask me why becuase I don’t really know) and found a repeatable error with a particular calculation, the cubed root of 64.

We all know that the cubed root of 64 is 4 (at least anyone likely to read my blog knows anyway) however the iPhone believes the cubed root of 64 is 4.000000000000001 which admittedly is pretty close to 4 but is strictly speaking still wrong.

Anyone care to shed some insight or ideas as to what might be causing this at a low level? I’m not looking for fixes, I’m not likely to use my iPhone for calculations that need that kind of accuracy but out of sheer curiosity I’d be interested to know how this could happen? Rounding errors in the code? How does one actually go about calculating the cubed root of a number? (it’s been a while since my math A-Level and I haven’t used it much since)

Answers on a postcard, or a comment below..