There are two things that always annoyed me about their calculators, so I just emailed them to see if they would change their design slightly. I said:
I teach maths and your calculators cause confusion because
1. They tell my students that -3 squared is -9
2. They tell my students that 100+10% (when typed in like this) equals 100.1
Please rectify these two points so that my students find maths just a little bit easier.
Just got this reply
Thank you for your enquiry.
Casio has passed this onto ourselves, as we are the leading authority on calculators used in UK schools.
All current twin-lines scientific calculators operate using the correct and precise priority of mathematical operations when a calculation is evaluated.
Squaring
Raising to the power 2 MUST take priority over the negative indicator (which is equivalent to multiplication by negative 1).
Verbally we often say “-3” have a slight pause “squared” which implies we are squaring by -3 but every calculator that uses the correct priority of will evaluate -3^2=-9.
Basic single-line scientific calculators operate on the displayed answer, so if -3 is shown then pressing the squaring key would operate on the whole of (-3), giving the result 9.
Percentages
Again, the calculator is mathematically precise 10%=0.1, so 100 + 10% = 100.1.
Some single-line calculators have a percentage shortcut that does allow you to add a percentage of the displayed amount. Different brands and models can have their own interpretations of a percentage key. In my teaching experience, I always banned my students from using a percentage key for this very reason.
In summary, the current range of Casio scientific calculators are designed to encourage accurate calculations using the correct mathematical syntax and priorities of operations. These are listed in the back of the User Guide for further reference.
Kind regards
Stephen
Stephen Kean
Science Studio
5 Lakeside Business Park
Middle Aston
Bicester
Oxon