text: how do convert centigrade temeratures to ferenheigh?   the answer "dbl and add 30" is incorrect.  a simple way that is 100% accurate is to double the c temperature, then subtract 1/10 of that number, then add 32.  for instance: 18 degrees c; double that and you have 36; subtract 1/10 of 36: 36 - 3.6 = 32.4.  now add 32.4 + 32 = 64.4.