HP 12C Questions


Hello to all,
I recently acquired a 12C for home use, because I took my 11C to the office to use in place of my 41C which is acting up, and my 35 won't hold a battery charge for long. The 12C did not come with a manual. I had assumed, being familiar with HP calculators, that I could figure out the basic functions of the 12C. All I really need for home use is basic arithmetic (balancing the checkbook, etc.). I know, it is like swatting a mosquito with a sledgehammer, but I much prefer the RPN operation to "other" calculators. The 12C passes the self-check and the keyboard check tests, so I assume that it is fully functional. However, I can't figure out how to get it to display any digits to the right of the decimal point. For example, I can type in 125.36, but when I push the ENTER key,it only displays 125. On my scientific HPs, I can set the number of digits to the right of the decimal point using the FIX key. I can't believe that a financial calculator cannot display dollars and cents! Also, whenever the 12C is on, the word BEGIN is appears in small letters at the bottom of the display; is this normal?


I believe that the number of digits past the decimal point is set by pressing the yellow shift key ("f"), then the corresponding number key for the desired number of digits. Try pressing the blue ("g") shift key, then the "8" key to get rid of the "BEGIN" annunciator in the display.



Jeff, thanks! That is exactly what I needed. Works like a charm now.


Randy, you say you recently "acquired" the 12c. Did you purchase it in a store, or get it from a friend or something? I ask this because 12c's have always come with a great manual, so I'm thinking you didn't buy this in a store, correct?

And since you said it passed the self-test, I'm thinking this is not one of the newer what we call the "12c+" which uses the ARM processor, has a small 6-pin connector in the battery compartment, has a problem with the self-test, and has an extra wide battery door to accomodate 2 CR-2032's. Yours must be an older 12c, correct?

You'll probably want to acquire the manual to get maximum benefit from the 12c. I suspect it's available online from HP.


Don, you are correct, it is not a new calculator. From some of the other correspondence in this forum, I am somewhat reluctant to admit that I bought it on ebay, for what I consider to be a reasonable price ($26). I only have the calculator and the case. Thank you for your suggestion regarding the manual; I was able to download not only the user's guide, but also the quick start guide, from the HP website.



it´s been more and more difficult to 'dig' specific information at HP calculators site...

The HP12C Manuals can be downloaded from this address.

About the standard (default) operating modes: you can set the HP12C to 'factory condition' by clearing all memory contents. If you are sure there is nothing stored in the calculator you need to keep, just do this: (if you own and use an HP11C, you already know the procedure...)

- with the calculator turned to off, press AND HOLD the [-] key;

- while holding the [-] key, turn the calculator ON;

- release the [-] key.

If everything goes fine, you would see [ Pr Error ] in the display of your calculator.

If you want your HP12C to show numbers in scientific notation, press:

[f] [.]

This is a scientific notation with all possible digits in the mantissa being shown. It is like the HP11C´s

[f][SCI][7] (or [8] or [9])
There is no way to control how many digits to be shown in the HP12C while in scientific notation (same as in the HP16C)

Hope this helps a bit more.


Luiz (Brazil)

Edited: 16 Jan 2010, 12:33 a.m.


HP 12c learning module PDFs

30 short PDF files covering how to do lots of things on the HP 12c at the above link.


Hi, Gene;

I tried to find these modules by searching the HP homepage, but I could not find them. Is it just me or this kind of information seems to be buried as time passes? 8^(


Luiz (Brazil)

Edited: 16 Jan 2010, 10:55 a.m.


You have to choose "calculators for school and business" and then the calculator pages have the learning modules. If you choose "home", they will be no where to be found.




Luiz, thanks very much for the information.


Do people still balance checkbooks? I have everything but the gardener on autopay from the bank. Even the dentist and Kaiser take credit cards. I had a $20,000 check disappear in the mail, we hand carry large ones now. Sam

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