Aussie Susan has a good point. If the sensor is linear you can create an algebraic equation to convert from AD reading to temperature. If it is non linear you are looking at more complex math.
What portion of the 16 bit AD value are you using? Do you need the full range of 65,535 units of discrimination? I doubt it. If resolution is reasonable a table read might be a rasonable idea. If the sensor is non linear review Microchip AN942 on Piecewise Linear Interpolation. I'm using that method on an altimeter than has 16 bit input. The pressure-altitude relationship is logarimithic.
Translating from a 16 bit number to display digits is straightforward. Take the AD number and subtract 10,000 until the result is negative. Add back the last 10,000 subtracted. The number you were able to subtract, before going negative, is the number of 10,000's to display. Repeat the process with 1000's, then 100's, then 10's to fill out your display digits.