You may have written the formula for converting from Celsius to Fahrenheit incorrectly. The formula is $\displaystyle{F}=\frac{{9}}{{5}}\cdot{C}+{32}\usepackage{cmbright}\Huge\$ , not $\displaystyle{F}=\frac{{5}}{{9}}\cdot{C}+{32}\usepackage{cmbright}\Huge\$ .