I've hit a road block in converting temperature from celcius to fahrenheit. I know:

ºF = (ºC*18)/10+32

This works fine for positve temperatures but not for negative. I discovered:

ºF = 32-((-ºC*18/10+32)-32)

This formula works fine until I get to the negative numbers in ºF. In ºC there is a bit set indicating that the number presented is a negative.

Any ideas would be greatly appreciated.