The Student Room Group

Calculator Problems Again…

My calculator (fx-991EX) gives me a decimal number and not the surd form when I write in qualities like cos(30) and it’s in degrees. My maths teachers haven’t been able to figure it out. Any help?
Original post by depriveofsocial
My calculator (fx-991EX) gives me a decimal number and not the surd form when I write in qualities like cos(30) and it’s in degrees. My maths teachers haven’t been able to figure it out. Any help?

You should check that the input/output option (Shift Menu 1) is set to Math I / Math O (option 1 on the list).
Original post by old_engineer
You should check that the input/output option (Shift Menu 1) is set to Math I / Math O (option 1 on the list).


just done that! it’s still giving me decimals for values such as cos(30)
Reply 3
Original post by depriveofsocial
just done that! it’s still giving me decimals for values such as cos(30)

maybe u just need to press the S=>D function?
Original post by aamina.hs
maybe u just need to press the S=>D function?


I’ve tried that, it doesn’t work unfortunately. It should come up with the surd first
Original post by depriveofsocial
just done that! it’s still giving me decimals for values such as cos(30)

What decimal value is it giving you for cos(30) ?
Reply 6
Maybe reset the calculator?
Original post by old_engineer
What decimal value is it giving you for cos(30) ?


0.8660254038
Original post by Methene
Maybe reset the calculator?


I’ve pressed menu, 9 (reset) and done all of three of the buttons, the memory, setup data and all, but i still dont get surd form
Reply 9
Original post by depriveofsocial
My calculator (fx-991EX) gives me a decimal number and not the surd form when I write in qualities like cos(30) and it’s in degrees. My maths teachers haven’t been able to figure it out. Any help?


Hi, I had the same issue with mine! Turns out the calculator was counterfeit so I’d suggest returning and getting a new one!
Reply 10
Original post by subbhy
Hi, I had the same issue with mine! Turns out the calculator was counterfeit so I’d suggest returning and getting a new one!

Casio has their own authentication test that you can find online to determine whether this is the case. There are loads of fake calculators around on the market 🙄
Original post by subbhy
Hi, I had the same issue with mine! Turns out the calculator was counterfeit so I’d suggest returning and getting a new one!


Thank you, just found out it’s a fake! However I bought it on amazon for around £30 in September..
Reply 12
Original post by depriveofsocial
Thank you, just found out it’s a fake! However I bought it on amazon for around £30 in September..


Oh damn, I got mine off eBay! And then bought one off Amazon which worked fine. Must have been a dodgy seller, hope you get a refund!

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