Someohow, my HP 12c has gotten a screen that says RPN in left corner and has 0.000, Problem: if i want to enter,say 16,459; the 4 doesnt appear. i don't know if that's a setting problem or jst something wrong w/ my 4 key. Just tried using 4 in other places and it works, so not a 'key' problem...any one have any ideas??

SOURCE: Keyboard HP 12c

Under the rubber membrane ,touching the individual symbols (in this case zero & plus[+] there is a carbon coating (black stuff) that shorts out the two metal connectors on the board, when u press down on the keys
Open hp12c and lift up membrane away from body and see if the metal contacts[on the body] are warned, damaged or that the " black stuff " is on the membrane.
u can try a fix...........take a small piece of aluminum foil and glue it to the underside of rubber membrane where the "stuff" was.
Don't put a thick piece because the metal foil should bounce back with the membrane as u press down on the key.
Hope that helps.
I tried this once.........a small dab[ hey!!,, when I say a dab....i mean a dab....of glue. Sharpen a pencil & rub the tip across a EMERY board so that the carbon "black stuff" from the pencil falls on top of the glue. Let it set & try for 2 hrs or more.
HOPE THAT HELPS!!!

SOURCE: I just replaced the batteries in my HP 12C

Hello,
Here is what the manual for the HP 12C Platimum financial calculator says on page 17 of 275

Digit Separators
As a number is keyed in, each group of three digits to the left of the decimal point is automatically separated in the display. When the calculator is first turned on after coming from the factory — or after Continuous Memory is reset — the decimal point in displayed numbers is a dot, and the separator between each group of three digits is a comma. If you wish, you can set the calculator to display a comma for the decimal point and a dot for the three-digit separator. To do so,
turn the calculator off, then press and hold down the [ . ] key while you press [ON] Doing so again sets the calculator to use the original digit separators in the display.

Hope it helps.

SOURCE: One of the keys on my 12c calculator keeps

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.

SOURCE: The keys stick on my HP 12C calculator so that

Try glass cleaner with a paper towel. If that doesn't work you'll have to take it apart and remove the button pad.

SOURCE: My HP 12C is displaying with a comma rather than a

Turn the calculator off. Press and hold down the decimal point while you press ON. The digit separator and radix sign will flip each time you do this.

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