20 Most Recent HP 12c Calculator Questions & Answers

It could be some dirt or grit in the keyboard, which a blast or two of compressed air might clear out. It could be a worn dome on the inside of the keyboard.
If you want to have it repaired, there's FixThatCalc, though they're currently not taking new orders. There also have been several threads on opening and cleaning Voyager series keyboards at the Museum of HP Calculators. Here's one article on opening a Voyager.

HP 12c... | Answered on Oct 07, 2018

my hp 12c stuck on -8.08 and below that was the "user" and "f" that you had. I had just put in 2 new, fresh Sony 2032 batteries. When I replaced the Sony batteries with generic ones - the calculater worked perfectly. Interestingly, those Sony batteries work fine in other gadgets so I don't understand why my hp 12c had a problems with them. But at least I fixed the problem.

HP 12c... | Answered on Jun 03, 2018

Couple of possibilities:
Dodgy power is the first thing to address. Get a replacement battery - 3V lithium CR 2032 type. Swap it for the current one. Check, while the system is open, if the battery and/or battery contacts look dull, corroded, or tarnished. If they do, you can try cleaning the battery contacts with a pencil eraser, or some fine steel wool (non-soapy kind) or fine sandpaper to brighten it.

2) You can reset memory to see if that has an effect. With calculator off, hold [On], then press [-] at same time. Still holding [-]. release [On], then release [On] May blink or flash for a couple tens of seconds. This will erase everything in memory, programs and saved calculations.

3) The general self-test is doing the same process as in (2), but with the [+] or [x] key instead of the [-] key. Should take 20-30 seconds and all sorts of things will flash or light up on the display while this happens. If the system thinks it's fine, you'll end up with the normal start display. Otherwise, there may be error messages. At that point, you might have to contact HP.

4) You can view the use manual (all 170+ pages of it) at http://www.hp.com/ctg/Manual/c00363319.pdf . Lord knows if the addresses for service are still valid.

Good Luck !

HP 12c... | Answered on Jun 03, 2018

I found this solution on the HP website. Turn it on, and do what it says. Then turn it off and back on again, and the extra decimal places should show.

http://h10025.www1.hp.com/ewfrf/wc/document?dlc=en&lc=en&cc=us&docname=bpia5183 Introduction This document describes how to set the desired number of decimal places on the HP 12C Calculator in standard format and in scientific notation. Instructions for standard format
  1. Press and release the gold PREFIX key (f).
  2. Press the number key for the desired number of decimal places (0 through 9).
The display will show the specified number of decimal places. The answer will be rounded to the number of digits selected.

HP 12c... | Answered on Feb 27, 2017

You could buy it on Ebay or on the HP website:)

HP 12c... | Answered on Jan 03, 2017

In addition to 1/2 =0.5, 1/3=0.33333333 , 1/4=0.25, 1/5=0.20 , 1/6=0.66666666666, 1/8= 0.125, 1/10 =0.1, there are two decimal numbers that are worth remembering because they are so easy to remember. These are
1/9 =0.111111111111111111111 ...
1/11 =0.099999999999999999999 .....
Your fraction is therefore equal to 1/9
I skimmed the whole manual but could not find a way to convert a decimal number to a fraction on the calculator. There are however two functions, one to extract the integer part [g][INTG], and the other [g][FRAC] to extract the fractiona part of a number.
Sorry. Hope it helps.

HP 12c... | Answered on Sep 27, 2016

The calculator is doing exactly what you tell it to,

You first input 1.06. Then you press the y*x key, which tells the calculator to raise the previous number on the stack to the 1.06 power. Then you input 10. The result of all this is 10, as your calculator shows.

If you want to raise 1.06 to the tenth power, press 1 . 0 6 ENTER 10 y^x.

My 12c shows 1.7908 for the above.

HP 12c... | Answered on Sep 09, 2016

Here is a link to one of my earlier posts where I show how to test proper operation of the calculator. I invite you to read it.

HP 12c... | Answered on Dec 11, 2015

clear ,clear ,clear and reenter correct .

HP 12c... | Answered on Aug 28, 2015

Set the display to 2 decimal places then use the [RND] function. See how the manual describes the Round operation.

23101423-rvrejqbjq4zuw4cbinsyjvsy-5-0.png Brief example:
01- 42 2 [f][2]
02- 42 14 [f][RND]
03- 42 9 [f][9]
The above program takes the number displayed and rounds to 2 decimal places (nearest 100th), then displays all decimal places.
If you entered 2.876 and ran the program, it would display 2.880000000.

HP 12c... | Answered on Jun 07, 2015

There is no contrast adjustment possible with the 12c. Most of the time, faint displays are due to weak batteries or poor contact with the battery or batteries.

HP 12c... | Answered on Jun 07, 2015

If you mean it is not showing everything after the decimal point, you can change that by pressing the [f] key followed by the number of decimal places to display. For example, to restrict it to 2 places, press [f][2]. If you want to see 4 places, press [f][4].

To show all possible decimal places, use the sequence [f][9].
From the manual (http://www.hp.com/ctg/Manual/c00363319.pdf):
"To display a different number of decimal places, press f followed by a digit key (0 through 9) specifying the number of decimal places. In the following examples, notice how the displayed form of the number inside the calculator - 14.87456320 - is rounded to the specified number of digits."

25096057-rvrejqbjq4zuw4cbinsyjvsy-5-0.png "Although nine decimal places were
specified after f, only eight are
displayed since the display can
show a total of only 10 digits. "
The standard display format, plus the specified number of decimal places, remain in effect until you change them; they are not reset each time the calculator is turned on. However, if Continuous Memory is reset, when the calculator is next turned on numbers will be displayed in the standard display format with two decimal places
If a calculated answer is either too small or too large to be displayed in the standard display format, the display format automatically switches to scientific notation. The display returns to the standard display format for all numbers that can be displayed in that format.

HP 12c... | Answered on Jun 07, 2015

From page 31 of the manual in English, available on HP's website at the link below:
Number of Days Between Dates
To calculate the number of days between two given dates:
1. Key in the earlier date and press [ENTER].
2. Key in the later date and press [g][?DYS].
The answer shown in the display is the actual number of days between the two dates, including leap days (the extra days occurring in leap years), if any. In addition, the hp 12c also calculates the number of days between the two dates on the basis of a 30-day month. This answer is held inside the calculator; to display it,
press [X><Y]. Pressing [X><Y]again will return the original answer to the display.


HP 12c... | Answered on Jun 04, 2015

There is an excellent computer-based tutorial for the HP 12c Platinum on HP's website (although the sequence for TVM calculations is the same for the original 12c).
Download it and have a look. It will guide you key-by-key through the steps.


HP 12c... | Answered on Jun 04, 2015

there should be a battery already installed in this calculator...

HP 12c... | Answered on Jan 07, 2015

That depends on the density of the substance.
11.5 tonnes of water is 11.5 cubic meters.
11.5 tonnes of gold is a little more than half a cubic meter.

HP 12c... | Answered on Oct 24, 2014

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