I can't explain all the things b'coz of some circumstances.

I m using 0 to 2V range as a i/p for ADC. So for full range i m getting C8 (1101 1000)as a output. My ultimate aim is to display 0 to 100 deg celcius on LCD display. So i want to convert C8 data to 100.
I m using and trying to implement eqn y= mx + c. i m doing calculations in decimal.
i.e. for i/p=2v (C8h or 200d), o/p=100, c=0
so it becomes
100 = m*200
so m= 0.5 I dont know how to deal with float variables in micro-controllers. So i m multiplying whatever data by 5 and later on displaying dot(decimal pt.)
so when C8 is multiplyed my 5 ans=3E8h=1000d (i wil be displaying 100.0)
So for converting this 3E8 h to decimal equivalent i want 16-bit hex to dec conversion code.
Sir, what do u think about my logic? is it right? Plz guide. I wil be very thankful to u.
Waiting for ur +ve reply.