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?

Reply 1

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).

Reply 2

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?

Reply 4

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

Reply 5

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?

Reply 7

Original post by old_engineer
What decimal value is it giving you for cos(30) ?


0.8660254038

Reply 8

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 🙄

Reply 11

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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