[whitelighter]

I'm having difficulty with the following problem using my Sharp EL-501x calculator:

What are the [H30+] and [OH-] of a beer that has a pH of 4.7?

I've followed the steps in the textbook exactly: I entered 4.7, then +/-, then '2nd function', then 10^x. I got 0.000019952, not even close to the answer in the text: 2.5 x 10^-5. My calculator doesn't have an 'inv' button so I can't use the optional 'inv' - 'log' method. Can anyone help?
It's not covered in the instruction manual.

[Corribus]

Have you considered the possibility that the problem isn't your calculator?

[Borek]

I got 0.000019952, not even close to the answer in the text: 2.5 x 10^-5.

Good. Text answer refers to pH 4.6.