i have problem​

i have A/D converter that convert anloge input to 8 bit
input analog come from voltage divider variable circuit that input 12volt alwas and it output with range of 0 to 12volt
i need to know that what the analog voltage input to A/DC from output of A/DC that preduce that output without using D/AC
i convert the output to BCD .... can tell me how i know the input voltage from BCD value that i have??????????????​

 

Your post is very hard to follow. Especially this:

i need to know that what the analog voltage input to A/DC from output of A/DC that preduce that output without using D/AC

The colors don't help much, either.

An 8 bit A to D has a maximum numeric output in binary. Dividing the full scale analog input by the A to D maximum value gives the resolution of each bit.

Be certain that the A to D has a BCD coded output and not binary. That will make an enormous difference.