Bill, you mention that you had to use FP to calculate, that's not necessary. You can save a lot of time and codespace by using ** instead. This operator makes your multiplication and an "invisible" division by 65536. Replace all your calculations with ......

ScaledResult = AccumulatedADvals ** 5000

to get 0 to 5.000 volts or .......

ScaledResult = AccumulatedADvals ** 15000

.... if yo want it to go from 0 to 15.000V instead.