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# How do Casio calculators return answers like "2π" without CAS? Watch

1. Hi,
I was wondering how Casio calculators can return fractional answers, answers with surds and answers in terms of pi without needing a CAS.
On my Casio fx-991ES PLUS it's easy to trick it into thinking it's dealing with pi by entering 3.14159265359, and it'll return "π" as the answer, where as on my HP 50g which actually has a CAS it isn't so easily fooled.
So my question is how does it work out these answers in this form without using an actual CAS?
Thanks.
2. (Original post by Wongdong)
Hi,
I was wondering how Casio calculators can return fractional answers, answers with surds and answers in terms of pi without needing a CAS.
On my Casio fx-991ES PLUS it's easy to trick it into thinking it's dealing with pi by entering 3.14159265359, and it'll return "π" as the answer, where as on my HP 50g which actually has a CAS it isn't so easily fooled.
So my question is how does it work out these answers in this form without using an actual CAS?
Thanks.
It isn't strictly doing algebra, but just numerical manipulation, since it has the values of pi, root2, etc. stored in memory.
Thus it effectively gets through the rules on a technicality.

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