PIC16f84 binary to bcd

for a class project, I need to take a 12-bit digital signal and output it as a decimal number to 4 7-segment displays. I know that the pic16f84 can take up to a 12-bit input if you use both ports a and b, but I dont know how to work with a 12-bit number since I can only store in 8bit registers.

Once I can work with my 12bit number i need to be able to convert it to bcd in order to use a lookup table for the output values. That is, unless there's a better way to do this.

If anyone has any suggestions or links to helpful pic programming websites I would be grateful. Thanks.

Oh ya, I'm programming in C.

Ignore the 12bit thing, I think I've got that covered.

If I've got a decimal value saved in memory how can I take each individual digit separately?

Here's the code i have so far:

TRISA = 0xff; //Set Port A to input
TRISB = 0xff; //Set Port B to input
inputLow = PORTB; //Take Port B input and save it to memory
lower = inputLow & 0x0f;
upper = inputLow & 0xf0 >> 4;
inputHigh = PORTA; //Take Port A input and save it to memory

n = inputHigh * pow(16,2) + upper * 16 + lower; //decimal value of input