How to fix my hp calculator 12c numbers display is faint?

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.


http://www.hp.com/ctg/Manual/c00363319.pdf

Press "f" then the digit representing the number of digits you want after the decimal point.

The HP 12C doesn't have a complex mode.

If you're seeing a "C" on the display, it means the calculator is set to use compound interest for the odd period. To switch to using simple interest, press STO followed by EEX.

Initial Setup

One adjustment is important before we get started. By default the 12C displays only two decimal places. This is not enough. Personally, I like to see five decimal places, but you may prefer some other number. To change the display, press "F" and then the number of decimal places you wish to display. I would press "F 5 " to display 5 decimal places. That's it, the calculator is ready to go.
You need to hold the "F" key.---------

1. Press and release the gold PREFIX key (f).
2. Press the number key for the desired number of decimal places (0 through 9).

------------ Click this link below and follow the procedure:--- http://howtobyme.blogspot.com/2011/07/hp-12c-calculator-help.html ----------- This should help.Thanks.Helpmech.

Press the f button then a digit specifying the number of digits you want after the decimal point. Be aware that numbers whose magnitude are too small or too large will always be shown in scientific notation so as to fit into the display.

Resetting the calculator using the keyboardThe easiest reset is done from the keyboard. To reset the calculator, follow the procedures below in the order presented.

1. Press ON to turn off the calculator.
2. Press and hold [ - ] .
3. Press and release ON .
4. Release [ - ] .
5. The screen will display “Pr Error ”
6. The calculator will reset to the default settings, and the memory will be erased.

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.

Check this HP FAQ:
Setting a Fixed Decimal Place You can download the manual and user guides for your calculator from here:
http://h10025.www1.hp.com/ewfrf/wc/manualCategory?lc=en&dlc=en&cc=us&product=81575&lang=en&

For more information, Faqs & how-Tosgo the HP support homepage for your calculator:
http://h10025.www1.hp.com/ewfrf/wc/product?lc=en&dlc=en&cc=us&lang=en&product=81575&

Introduction This document describes how to set the desired number of decimal places on the HP 12c calculator in standard format. It also covers how to enter a number in scientific notation. Instructions for standard format

1. Press and release .
2. Press the number key for the desired number of decimal places to be displayed to the right of the decimal point (0 through 9). The calculator displays a maximum of 10 digits.

The display will show the specified number of decimal places. The answer will be rounded to the number of digits selected. Example (standard format) If the number in the display is 14.87456320, the display will be changed as follows: Keystroke Display 14.8746 14.9 15 14.87456320 Instructions for scientific notation Use scientific notation for very large or very small numbers. Type in the mantissa. After pressing, the next numbers keyed in are exponents of 10. Press . If during an operation a result has more than 10 digits, the calculator automatically displays the number in scientific notation

Introduction This document describes how to set the desired number of decimal places on the HP 12c calculator in standard format. It also covers how to enter a number in scientific notation. Instructions for standard format

1. Press and release .
2. Press the number key for the desired number of decimal places to be displayed to the right of the decimal point (0 through 9). The calculator displays a maximum of 10 digits.

The display will show the specified number of decimal places. The answer will be rounded to the number of digits selected. Example (standard format) If the number in the display is 14.87456320, the display will be changed as follows: Keystroke Display 14.8746 14.9 15 14.87456320 Instructions for scientific notation Use scientific notation for very large or very small numbers. Type in the mantissa. After pressing, the next numbers keyed in are exponents of 10. Press . If during an operation a result has more than 10 digits, the calculator automatically displays the number in scientific notation

Begin - Press the blue "g" button then 8 ("end") to remove begin. Press the blue "g" and 7 ("BEG") to toggle back to having "Begin on display.

It's been awhile since I used one of these but there should be a decimal function on the keys. Make sure you put a 2 in there before pressing it and it should display the format using 200.00