There is a button in a vintage textbook showing a calculator with a "FIX" button. What was that button for?

The display is upside down probably because the calculator was subjected to a hacking procedure. Try to undo it or buy another calculator.

That is what you will get if your calculator is configured for the Line IO mode. If you want fractions to appear as in a textbook, you should configure your calculator's Input/Output mode to be MathIO. To do so press [SHIFT][MODE] to enter (SetUp) and select [1:MathIO]

On the 30XIIs, it's the key marked (-) just to the right of the decimal point key.

There's nothing wrong, the calculator just has the newest version of the operating system. To tell the calculator you're finished entering the exponent, simply press the right-arrow. If you don't want the new MathPrint mode, press MODE, press up-arrow to get to the second page, keep pressing up-arrow to get to the top line, highlight CLASSIC, press ENTER, then press 2ND [QUIT]. Now the calculator will display as the older operating system did.

The new MathPrint mode shows exponents, roots, fractions, and other things more like they appear in textbooks.

You're in MthIO mode, which comes closer to what you see in textbooks, where the calculator can show superscripts, fractions, etc. To get back to single-line mode, press SHIFT MODE 2 to select LineIO mode.

Here is the link to the calculator manual. It will show you how to do square root calculations, percentages, other roots, and logs. As to ratios and proportions you will have to read your mathematics textbook.

Hello,
If you use Mode [MathIO] the expressions are displayed as you will find them written in textbooks (Textbook display). You can readily see if that is what you had in mind.
To set MathIO press [Shift][Mode][1:MathIO]
Hope it helps.

You can change the amount of the numbers after the point.

You don't need a cpt button on Hp 10ii calculator.You can just press the function button that you want to apply without pressing cpt first.

Just input #20 then press log button then (2/10 shift 5 (m)) so it will look like 20log (2/10m) = 46.02