Temperature measurement using LM35
It appears that the reading has already been scaled by the software, since the 315 ADC reading you are seeing is very close to the 312 you'd expect with a room temperature of 31.2°C (which, in turn, seems about 10°C too hot for comfort, but that's just my opinion).

As you've found, you only need to divide the number (which is the mV) by 10.0 (mV/°C) to get the temperature in Celsius.