Whats the calculator doing?

KAGY

First of all I know the syntax is wrong, but I've seen student do this and i can't work out what the calculator is actually calculating. Casio Fx83

Say student is trying to work out 200 less 10%, and types in 200 - 10 (shift) %
The answer comes up as 1900 ?!? similary addition would be 2100
To make it even more confusing 200-50% = 300 200-1%=19900
50% is 50, but 0+50% = 100 infact 0 plus any% =100

So what is the calculator actually doing?

(yes I know I should be inputting 200x90% or 200-200*10% or even 200*10%-)

CJC86

200 - 10 = 190, which is 1900% of 10.
200 - 50 = 150, 300% of 50 etc.

bnt

That % shortcut method isn't going to work on an "algebraic entry" calculator like the FX-83. I have the FX-991ES, which has a similar system, and if I do 200-10%, it gives me 199.9, because the 10% is converted to 0.1, so 200-0.1=199.9. The manual appendix says to spell out the whole calculation, so I'd do 200-200x10% = 180.

(Any of your students using RPN? 200 ENTER 10 % - :cool: )

Thomas_S_Hunterson

bnt wrote: »

(Any of your students using RPN? 200 ENTER 10 % - :cool: )

I'd say the (crazy) going rate for a basic RPN calc puts it well beyond what parents of the average student is willing to pay. That said, I'm not aware of what's in the market beyond HP's offering.

bnt

Well, I got a HP 35s last year, which isn't bad, but there are free computer ones out there too. e.g. Complex RPN Calc for the iPhone / iPod Touch etc. But even if students could afford a HP, all their RPN calculators are programmable and therefore not permitted in exams. Oh well ...